diff --git a/ANNOUNCE b/ANNOUNCE
index 330fd10..262ff11 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.25 - September 1, 2016
+Libpng 1.6.26 - October 20, 2016
 
 This is a public release of libpng, intended for use in production codes.
 
@@ -7,30 +7,55 @@
 Source files with LF line endings (for Unix/Linux) and with a
 "configure" script
 
-   libpng-1.6.25.tar.xz (LZMA-compressed, recommended)
-   libpng-1.6.25.tar.gz
+   libpng-1.6.26.tar.xz (LZMA-compressed, recommended)
+   libpng-1.6.26.tar.gz
 
 Source files with CRLF line endings (for Windows), without the
 "configure" script
 
-   lpng1625.7z  (LZMA-compressed, recommended)
-   lpng1625.zip
+   lpng1626.7z  (LZMA-compressed, recommended)
+   lpng1626.zip
 
 Other information:
 
-   libpng-1.6.25-README.txt
-   libpng-1.6.25-LICENSE.txt
-   libpng-1.6.25-*.asc (armored detached GPG signatures)
+   libpng-1.6.26-README.txt
+   libpng-1.6.26-LICENSE.txt
+   libpng-1.6.26-*.asc (armored detached GPG signatures)
 
-Changes since the last public release (1.6.24):
-  Reject oversized iCCP profile immediately.
-  Cleaned up PNG_DEBUG compile of pngtest.c.
-  Conditionally compile png_inflate().
-  Don't install pngcp; it conflicts with pngcp in the pngtools package.
-  Minor editing of INSTALL, (whitespace, added copyright line)
-  Added MIPS support (Mandar Sahastrabuddhe <Mandar.Sahastrabuddhe@imgtec.com>).
-  Rebased contrib/intel/intel_sse.patch after the MIPS implementation.
+Changes since the last public release (1.6.25):
 
+  Fixed handling zero length IDAT in pngfix (bug report by Agostino Sarubbo,
+    bugfix by John Bowler).
+  Do not issue a png_error() on read in png_set_pCAL() because png_handle_pCAL
+    has allocated memory that libpng needs to free.
+  Conditionally compile png_set_benign_errors() in pngread.c and pngtest.c
+  Issue a png_benign_error instead of a png_error on ADLER32 mismatch
+    while decoding compressed data chunks.
+  Changed PNG_ZLIB_VERNUM to ZLIB_VERNUM in pngpriv.h, pngstruct.h, and
+    pngrutil.c.
+  If CRC handling of critical chunks has been set to PNG_CRC_QUIET_USE,
+    ignore the ADLER32 checksum in the IDAT chunk as well as the chunk CRCs.
+  Issue png_benign_error() on ADLER32 checksum mismatch instead of png_error().
+  Add tests/badcrc.png and tests/badadler.png to tests/pngtest.
+  Merged pngtest.c with libpng-1.7.0beta84/pngtest.c
+  Updated the documentation about CRC and ADLER32 handling.
+  Quieted 117 warnings from clang-3.8 in pngtrans.c, pngread.c,
+     pngwrite.c, pngunknown.c, and pngvalid.c.
+  Quieted the 144 remaining -Wconversion compiler warnings by
+    revising the png_isaligned() macro and trivial changes in png.c,
+    pngerror.c, pngget.c, pngmem.c, pngset.c, pngrtran.c, pngrutil.c,
+    pngwtran.c, pngwrite.c, and pngwutil.c.
+  Quieted (bogus?) clang warnings about "absolute value has no effect"
+    when PNG_USE_ABS is defined.
+  Fixed offsets in contrib/intel/intel_sse.patch
+  Changed integer constant 4294967294 to unsigned 4294967294U in pngconf.h
+    to avoid a signed/unsigned compare in the preprocessor.
+  Use zlib-1.2.8.1 inflateValidate() instead of inflateReset2() to
+    optionally avoid ADLER32 evaluation.
+  Cosmetic change, "ptr != 0" to "ptr != NULL" in png.c and pngrutil.c
+  Despammed email addresses (replaced "@" with " at ").
+
+Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
 to subscribe)
diff --git a/CHANGES b/CHANGES
index 923fc50..9dd82b4 100644
--- a/CHANGES
+++ b/CHANGES
@@ -593,7 +593,7 @@
     with trailing compressed parts easier in the future, and added new functions
     png_free_iCCP, png_free_pCAL, png_free_sPLT, png_free_text, png_get_iCCP,
     png_get_spalettes, png_set_iCCP, png_set_spalettes (Eric S. Raymond).
-  NOTE: Applications that write text chunks MUST define png_text->lang
+    NOTE: Applications that write text chunks MUST define png_text->lang
     before calling png_set_text(). It must be set to NULL if you want to
     write tEXt or zTXt chunks.  If you want your application to be able to
     run with older versions of libpng, use
@@ -5703,6 +5703,57 @@
 Version 1.6.25 [September 1, 2016]
   No changes.
 
+Version 1.6.26beta01 [September 26, 2016]
+  Fixed handling zero length IDAT in pngfix (bug report by Agostino Sarubbo,
+    bugfix by John Bowler).
+  Do not issue a png_error() on read in png_set_pCAL() because png_handle_pCAL
+    has allocated memory that libpng needs to free.
+  Conditionally compile png_set_benign_errors() in pngread.c and pngtest.c
+  Issue a png_benign_error instead of a png_error on ADLER32 mismatch
+    while decoding compressed data chunks.
+  Changed PNG_ZLIB_VERNUM to ZLIB_VERNUM in pngpriv.h, pngstruct.h, and
+    pngrutil.c.
+  If CRC handling of critical chunks has been set to PNG_CRC_QUIET_USE,
+    ignore the ADLER32 checksum in the IDAT chunk as well as the chunk CRCs.
+  Issue png_benign_error() on ADLER32 checksum mismatch instead of png_error().
+  Add tests/badcrc.png and tests/badadler.png to tests/pngtest.
+  Merged pngtest.c with libpng-1.7.0beta84/pngtest.c
+
+Version 1.6.26beta02 [October 1, 2016]
+  Updated the documentation about CRC and ADLER32 handling.
+  Quieted 117 warnings from clang-3.8 in pngtrans.c, pngread.c,
+     pngwrite.c, pngunknown.c, and pngvalid.c.
+  Quieted 58 (out of 144) -Wconversion compiler warnings by changing
+    flag definitions in pngpriv.h from 0xnnnn to 0xnnnnU and trivial changes
+    in png.c, pngread.c, and pngwutil.c.
+
+Version 1.6.26beta03 [October 2, 2016]
+  Removed contrib/libtests/*.orig and *.rej that slipped into the tarballs.
+  Quieted the 86 remaining -Wconversion compiler warnings by
+    revising the png_isaligned() macro and trivial changes in png.c,
+    pngerror.c, pngget.c, pngmem.c, pngset.c, pngrtran.c, pngrutil.c,
+    pngwtran.c, pngwrite.c, and pngwutil.c.
+
+Version 1.6.26beta04 [October 3, 2016]
+  Quieted (bogus?) clang warnings about "absolute value has no effect"
+    when PNG_USE_ABS is defined.
+  Fixed offsets in contrib/intel/intel_sse.patch
+
+Version 1.6.26beta05 [October 6, 2016]
+  Changed integer constant 4294967294 to unsigned 4294967294U in pngconf.h
+    to avoid a signed/unsigned compare in the preprocessor.
+
+Version 1.6.26beta06 [October 7, 2016]
+  Use zlib-1.2.8.1 inflateValidate() instead of inflateReset2() to
+    optionally avoid ADLER32 evaluation.
+
+Version 1.6.26rc01 [October 12, 2016]
+  No changes.
+
+Version 1.6.26 [October 20, 2016]
+  Cosmetic change, "ptr != 0" to "ptr != NULL" in png.c and pngrutil.c
+  Despammed email addresses (replaced "@" with " at ").
+
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
diff --git a/CMakeLists.txt b/CMakeLists.txt
index eb63b2b..c7878f6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -35,7 +35,7 @@
 
 set(PNGLIB_MAJOR 1)
 set(PNGLIB_MINOR 6)
-set(PNGLIB_RELEASE 25)
+set(PNGLIB_RELEASE 26)
 set(PNGLIB_NAME libpng${PNGLIB_MAJOR}${PNGLIB_MINOR})
 set(PNGLIB_VERSION ${PNGLIB_MAJOR}.${PNGLIB_MINOR}.${PNGLIB_RELEASE})
 
@@ -696,7 +696,7 @@
 # SET UP LINKS
 if(PNG_SHARED)
   set_target_properties(png PROPERTIES
-#   VERSION 16.${PNGLIB_RELEASE}.1.6.25
+#   VERSION 16.${PNGLIB_RELEASE}.1.6.26
     VERSION 16.${PNGLIB_RELEASE}.0
     SOVERSION 16
     CLEAN_DIRECT_OUTPUT 1)
diff --git a/LICENSE b/LICENSE
index d48a293..08e3129 100644
--- a/LICENSE
+++ b/LICENSE
@@ -10,7 +10,7 @@
 
 This code is released under the libpng license.
 
-libpng versions 1.0.7, July 1, 2000 through 1.6.25, September 1, 2016 are
+libpng versions 1.0.7, July 1, 2000 through 1.6.26, October 20, 2016 are
 Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
@@ -127,4 +127,4 @@
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-September 1, 2016
+October 20, 2016
diff --git a/Makefile.am b/Makefile.am
index fb209ed..356704d 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -1,7 +1,7 @@
 # Makefile.am, the source file for Makefile.in (and hence Makefile), is
 #
 # Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [September 1, 2016]
+# Last changed in libpng 1.6.25 [October 20, 2016]
 #
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
diff --git a/README b/README
index 17bca9a..709c269 100644
--- a/README
+++ b/README
@@ -1,4 +1,4 @@
-README for libpng version 1.6.25 - September 1, 2016 (shared library 16.0)
+README for libpng version 1.6.26 - October 20, 2016 (shared library 16.0)
 See the note about version numbers near the top of png.h
 
 See INSTALL for instructions on how to install libpng.
diff --git a/configure.ac b/configure.ac
index 83c5fc2..83183ab 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,7 +1,7 @@
 # configure.ac
 
 # Copyright (c) 2004-2016 Glenn Randers-Pehrson
-# Last changed in libpng 1.6.25 [September 1, 2016]
+# Last changed in libpng 1.6.25 [October 20, 2016]
 
 # This code is released under the libpng license.
 # For conditions of distribution and use, see the disclaimer
@@ -25,7 +25,7 @@
 
 dnl Version number stuff here:
 
-AC_INIT([libpng],[1.6.25],[png-mng-implement@lists.sourceforge.net])
+AC_INIT([libpng],[1.6.26],[png-mng-implement@lists.sourceforge.net])
 AC_CONFIG_MACRO_DIR([scripts])
 
 # libpng does not follow GNU file name conventions (hence 'foreign')
@@ -46,10 +46,10 @@
 dnl AM_PREREQ([1.11.2])
 dnl stop configure from automagically running automake
 
-PNGLIB_VERSION=1.6.25
+PNGLIB_VERSION=1.6.26
 PNGLIB_MAJOR=1
 PNGLIB_MINOR=6
-PNGLIB_RELEASE=25
+PNGLIB_RELEASE=26
 
 dnl End of version number stuff
 
diff --git a/contrib/examples/README.txt b/contrib/examples/README.txt
index 0525c9d..48dab4f 100644
--- a/contrib/examples/README.txt
+++ b/contrib/examples/README.txt
@@ -21,4 +21,4 @@
     of the people below claim any rights with regard to the contents of this
     directory.
 
-    John Bowler <jbowler@acm.org>
+    John Bowler <jbowler at acm.org>
diff --git a/contrib/gregbook/README b/contrib/gregbook/README
index 7b1f6a3..fd30f05 100644
--- a/contrib/gregbook/README
+++ b/contrib/gregbook/README
@@ -15,7 +15,7 @@
 
 The source code for all three demo programs currently compiles under
 Unix, OpenVMS, and 32-bit Windows.  (Special thanks to Martin Zinser,
-zinser@decus.de, for making the necessary changes for OpenVMS and for
+zinser at decus.de, for making the necessary changes for OpenVMS and for
 providing an appropriate build script.)  Build instructions can be found
 below.
 
diff --git a/contrib/gregbook/rpng-win.c b/contrib/gregbook/rpng-win.c
index f53ddc8..cd55439 100644
--- a/contrib/gregbook/rpng-win.c
+++ b/contrib/gregbook/rpng-win.c
@@ -182,7 +182,7 @@
 #ifndef __CYGWIN__
     /* First reenable console output, which normally goes to the bit bucket
      * for windowed apps.  Closing the console window will terminate the
-     * app.  Thanks to David.Geldreich@realviz.com for supplying the magical
+     * app.  Thanks to David.Geldreich at realviz.com for supplying the magical
      * incantation. */
 
     AllocConsole();
diff --git a/contrib/gregbook/rpng2-win.c b/contrib/gregbook/rpng2-win.c
index a7b9dfa..c924c1c 100644
--- a/contrib/gregbook/rpng2-win.c
+++ b/contrib/gregbook/rpng2-win.c
@@ -301,7 +301,7 @@
 #ifndef __CYGWIN__
     /* Next reenable console output, which normally goes to the bit bucket
      * for windowed apps.  Closing the console window will terminate the
-     * app.  Thanks to David.Geldreich@realviz.com for supplying the magical
+     * app.  Thanks to David.Geldreich at realviz.com for supplying the magical
      * incantation. */
 
     AllocConsole();
diff --git a/contrib/intel/intel_sse.patch b/contrib/intel/intel_sse.patch
index a852538..24d4883 100644
--- a/contrib/intel/intel_sse.patch
+++ b/contrib/intel/intel_sse.patch
@@ -134,7 +134,7 @@
  #        elif defined(__GNUC__)
  #           if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 7)
  #              define PNG_MIPS_MSA_IMPLEMENTATION 2
-@@ -1232,16 +1268,31 @@ PNG_INTERNAL_FUNCTION(void,png_read_filt
+@@ -1251,16 +1287,31 @@ PNG_INTERNAL_FUNCTION(void,png_read_filt
  PNG_INTERNAL_FUNCTION(void,png_read_filter_row_avg4_msa,(png_row_infop
      row_info, png_bytep row, png_const_bytep prev_row),PNG_EMPTY);
  PNG_INTERNAL_FUNCTION(void,png_read_filter_row_paeth3_msa,(png_row_infop
@@ -166,7 +166,7 @@
  PNG_INTERNAL_FUNCTION(void,png_read_IDAT_data,(png_structrp png_ptr,
     png_bytep output, png_alloc_size_t avail_out),PNG_EMPTY);
     /* Read 'avail_out' bytes of data from the IDAT stream.  If the output buffer
-@@ -1967,16 +2018,21 @@ PNG_INTERNAL_FUNCTION(void, PNG_FILTER_O
+@@ -1986,16 +2037,21 @@ PNG_INTERNAL_FUNCTION(void, PNG_FILTER_O
  PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
     (png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
  #endif
diff --git a/contrib/libtests/pngunknown.c b/contrib/libtests/pngunknown.c
index 8b15282..aba605e 100644
--- a/contrib/libtests/pngunknown.c
+++ b/contrib/libtests/pngunknown.c
@@ -1,7 +1,7 @@
 
 /* pngunknown.c - test the read side unknown chunk handling
  *
- * Last changed in libpng 1.6.22 [May 26, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 2015,2016 Glenn Randers-Pehrson
  * Written by John Cunningham Bowler
  *
@@ -478,7 +478,7 @@
       png_textp text;
       png_uint_32 ntext = png_get_text(d->png_ptr, info_ptr, &text, NULL);
 
-      while (ntext-- > 0) switch (text[ntext].compression)
+      while (ntext > 0) switch (text[--ntext].compression)
       {
          case -1:
             flags |= PNG_INFO_tEXt;
diff --git a/contrib/libtests/pngvalid.c b/contrib/libtests/pngvalid.c
index 9d3beb5..9b85c3e 100644
--- a/contrib/libtests/pngvalid.c
+++ b/contrib/libtests/pngvalid.c
@@ -1,9 +1,8 @@
 
 /* pngvalid.c - validate libpng by constructing then reading png files.
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
- * Copyright (c) 2014-2016 Glenn Randers-Pehrson
- * Written by John Cunningham Bowler
+ * Last changed in libpng 1.6.26 [October 20, 2016]
+ * Copyright (c) 2014-2016 John Cunningham Bowler
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -1242,7 +1241,7 @@
 
       image += 2; /* skip image first row markers */
 
-      while (rows-- > 0)
+      for (; rows > 0; --rows)
       {
          if (image[-2] != 190 || image[-1] != 239)
             png_error(pp, "row start overwritten");
@@ -11427,23 +11426,36 @@
        */
       for (v=0;;)
       {
+         /* The first two tests overflow if the pass row or column is outside
+          * the possible range for a 32-bit result.  In fact the values should
+          * never be outside the range for a 31-bit result, but checking for 32
+          * bits here ensures that if an app uses a bogus pass row or column
+          * (just so long as it fits in a 32 bit integer) it won't get a
+          * possibly dangerous overflow.
+          */
          /* First the base 0 stuff: */
-         m = PNG_ROW_FROM_PASS_ROW(v, pass);
-         f = png_row_from_pass_row(v, pass);
-         if (m != f)
+         if (v < png_pass_rows(0xFFFFFFFFU, pass))
          {
-            fprintf(stderr, "PNG_ROW_FROM_PASS_ROW(%u, %d) = %u != %x\n",
-               v, pass, m, f);
-            exit(99);
+            m = PNG_ROW_FROM_PASS_ROW(v, pass);
+            f = png_row_from_pass_row(v, pass);
+            if (m != f)
+            {
+               fprintf(stderr, "PNG_ROW_FROM_PASS_ROW(%u, %d) = %u != %x\n",
+                  v, pass, m, f);
+               exit(99);
+            }
          }
 
-         m = PNG_COL_FROM_PASS_COL(v, pass);
-         f = png_col_from_pass_col(v, pass);
-         if (m != f)
+         if (v < png_pass_cols(0xFFFFFFFFU, pass))
          {
-            fprintf(stderr, "PNG_COL_FROM_PASS_COL(%u, %d) = %u != %x\n",
-               v, pass, m, f);
-            exit(99);
+            m = PNG_COL_FROM_PASS_COL(v, pass);
+            f = png_col_from_pass_col(v, pass);
+            if (m != f)
+            {
+               fprintf(stderr, "PNG_COL_FROM_PASS_COL(%u, %d) = %u != %x\n",
+                  v, pass, m, f);
+               exit(99);
+            }
          }
 
          m = PNG_ROW_IN_INTERLACE_PASS(v, pass);
diff --git a/contrib/pngminus/README b/contrib/pngminus/README
index bbe7407..fbcfc98 100644
--- a/contrib/pngminus/README
+++ b/contrib/pngminus/README
@@ -146,7 +146,7 @@
 The end
 -------
 Willem van Schaik
-mailto:willem@schaik.com
+mailto:willem at schaik.com
 http://www.schaik.com/png/
 -------
 Oct 1999
diff --git a/contrib/pngminus/png2pnm.c b/contrib/pngminus/png2pnm.c
index f68d7ff..995fddf 100644
--- a/contrib/pngminus/png2pnm.c
+++ b/contrib/pngminus/png2pnm.c
@@ -1,6 +1,6 @@
 /*
  *  png2pnm.c --- conversion from PNG-file to PGM/PPM-file
- *  copyright (C) 1999 by Willem van Schaik <willem@schaik.com>
+ *  copyright (C) 1999 by Willem van Schaik <willem at schaik.com>
  *
  *  version 1.0 - 1999.10.15 - First version.
  *
diff --git a/contrib/pngminus/pnm2png.c b/contrib/pngminus/pnm2png.c
index 8fa64cd..5de828a 100644
--- a/contrib/pngminus/pnm2png.c
+++ b/contrib/pngminus/pnm2png.c
@@ -1,6 +1,6 @@
 /*
  *  pnm2png.c --- conversion from PBM/PGM/PPM-file to PNG-file
- *  copyright (C) 1999 by Willem van Schaik <willem@schaik.com>
+ *  copyright (C) 1999 by Willem van Schaik <willem at schaik.com>
  *
  *  version 1.0 - 1999.10.15 - First version.
  *  version 1.1 - 2015.07.29 - Fixed leaks (Glenn Randers-Pehrson)
diff --git a/contrib/pngsuite/README b/contrib/pngsuite/README
index a7fde8f..53ba5c8 100644
--- a/contrib/pngsuite/README
+++ b/contrib/pngsuite/README
@@ -101,5 +101,5 @@
 libpng passes test
 
 Willem van Schaik
-<willem@schaik.com>
+<willem at schaik.com>
 October 1999
diff --git a/contrib/tools/README.txt b/contrib/tools/README.txt
index 5ddae02..f53be6d 100644
--- a/contrib/tools/README.txt
+++ b/contrib/tools/README.txt
@@ -23,4 +23,5 @@
     of the people below claim any rights with regard to the contents of this
     directory.
 
-    John Bowler <jbowler@acm.org>
+    John Bowler <jbowler at acm.org>
+    Glenn Randers-Pehrson <glennrp at users.sourceforge.net>
diff --git a/contrib/tools/pngfix.c b/contrib/tools/pngfix.c
index b2043e3..6da970c 100644
--- a/contrib/tools/pngfix.c
+++ b/contrib/tools/pngfix.c
@@ -2,7 +2,7 @@
  *
  * Copyright (c) 2014-2016 John Cunningham Bowler
  *
- * Last changed in libpng 1.6.21 [January 15, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
@@ -1824,7 +1824,7 @@
 }
 
 static png_uint_32
-rechunk_length(struct IDAT *idat)
+rechunk_length(struct IDAT *idat, int start)
    /* Return the length for the next IDAT chunk, taking into account
     * rechunking.
     */
@@ -1836,7 +1836,7 @@
       const struct IDAT_list *cur;
       unsigned int count;
 
-      if (idat->idat_index == 0) /* at the new chunk (first time) */
+      if (start)
          return idat->idat_length; /* use the cache */
 
       /* Otherwise rechunk_length is called at the end of a chunk for the length
@@ -1995,7 +1995,7 @@
       idat->idat_index = 0; /* Index into chunk data */
 
       /* Update the chunk length to the correct value for the IDAT chunk: */
-      file->chunk->chunk_length = rechunk_length(idat);
+      file->chunk->chunk_length = rechunk_length(idat, 1/*start*/);
 
       /* Change the state to writing IDAT chunks */
       file->state = STATE_IDAT;
@@ -3473,7 +3473,8 @@
                      /* Write another IDAT chunk.  Call rechunk_length to
                       * calculate the length required.
                       */
-                     length = chunk->chunk_length = rechunk_length(file->idat);
+                     length = chunk->chunk_length =
+                         rechunk_length(file->idat, 0/*end*/);
                      assert(type == png_IDAT);
                      file->write_count = 0; /* for the new chunk */
                      --(file->write_count); /* fake out the increment below */
diff --git a/libpng-manual.txt b/libpng-manual.txt
index d969f96..a5cd8ee 100644
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1,6 +1,6 @@
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.6.25 - September 1, 2016
+ libpng version 1.6.26 - October 20, 2016
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2016 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.6.25 - September 1, 2016
+ libpng versions 0.97, January 1998, through 1.6.26 - October 20, 2016
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2016 Glenn Randers-Pehrson
 
@@ -467,8 +467,9 @@
 
 The values for png_set_crc_action() say how libpng is to handle CRC errors in
 ancillary and critical chunks, and whether to use the data contained
-therein.  Note that it is impossible to "discard" data in a critical
-chunk.
+therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
+is handled while reading the IDAT chunk. Note that it is impossible to
+"discard" data in a critical chunk.
 
 Choices for (int) crit_action are
    PNG_CRC_DEFAULT      0  error/quit
@@ -485,6 +486,9 @@
    PNG_CRC_QUIET_USE    4  quiet/use data
    PNG_CRC_NO_CHANGE    5  use the current value
 
+When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
+checksums are not only ignored, but they are not evaluated.
+
 Setting up callback code
 
 You can set up a callback function to handle any unknown chunks in the
@@ -5335,8 +5339,9 @@
 We prefer to use underscores rather than camelCase in names, except
 for a few type names that we inherit from zlib.h.
 
-We prefer "if (something != 0)" and "if (something == 0)"
-over "if (something)" and if "(!something)", respectively.
+We prefer "if (something != 0)" and "if (something == 0)" over
+"if (something)" and if "(!something)", respectively, and for pointers
+we prefer "if (some_pointer != NULL)" or "if (some_pointer == NULL)". 
 
 We do not use the TAB character for indentation in the C sources.
 
@@ -5350,7 +5355,7 @@
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.25 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.26 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has two year fields.  One is a 2-byte unsigned integer
diff --git a/libpng.3 b/libpng.3
index 4893dc9..ce06bce 100644
--- a/libpng.3
+++ b/libpng.3
@@ -1,6 +1,6 @@
-.TH LIBPNG 3 "September 1, 2016"
+.TH LIBPNG 3 "October 20, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.25
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.26
 .SH SYNOPSIS
 \fB
 #include <png.h>\fP
@@ -510,7 +510,7 @@
 .SH LIBPNG.TXT
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.6.25 - September 1, 2016
+ libpng version 1.6.26 - October 20, 2016
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2016 Glenn Randers-Pehrson
@@ -521,7 +521,7 @@
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.6.25 - September 1, 2016
+ libpng versions 0.97, January 1998, through 1.6.26 - October 20, 2016
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2016 Glenn Randers-Pehrson
 
@@ -977,8 +977,9 @@
 
 The values for png_set_crc_action() say how libpng is to handle CRC errors in
 ancillary and critical chunks, and whether to use the data contained
-therein.  Note that it is impossible to "discard" data in a critical
-chunk.
+therein. Starting with libpng-1.6.26, this also governs how an ADLER32 error
+is handled while reading the IDAT chunk. Note that it is impossible to
+"discard" data in a critical chunk.
 
 Choices for (int) crit_action are
    PNG_CRC_DEFAULT      0  error/quit
@@ -995,6 +996,9 @@
    PNG_CRC_QUIET_USE    4  quiet/use data
    PNG_CRC_NO_CHANGE    5  use the current value
 
+When the setting for crit_action is PNG_CRC_QUIET_USE, the CRC and ADLER32
+checksums are not only ignored, but they are not evaluated.
+
 .SS Setting up callback code
 
 You can set up a callback function to handle any unknown chunks in the
@@ -5845,8 +5849,9 @@
 We prefer to use underscores rather than camelCase in names, except
 for a few type names that we inherit from zlib.h.
 
-We prefer "if (something != 0)" and "if (something == 0)"
-over "if (something)" and if "(!something)", respectively.
+We prefer "if (something != 0)" and "if (something == 0)" over
+"if (something)" and if "(!something)", respectively, and for pointers
+we prefer "if (some_pointer != NULL)" or "if (some_pointer == NULL)". 
 
 We do not use the TAB character for indentation in the C sources.
 
@@ -5860,7 +5865,7 @@
 an official declaration.
 
 This is your unofficial assurance that libpng from version 0.71 and
-upward through 1.6.25 are Y2K compliant.  It is my belief that earlier
+upward through 1.6.26 are Y2K compliant.  It is my belief that earlier
 versions were also Y2K compliant.
 
 Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -5962,7 +5967,7 @@
  ...
  1.5.27                  15    10527  15.so.15.27[.0]
  ...
- 1.6.25                  16    10625  16.so.16.25[.0]
+ 1.6.26                  16    10626  16.so.16.26[.0]
 
 Henceforth the source version will match the shared-library minor
 and patch numbers; the shared-library major version number will be
@@ -6018,7 +6023,7 @@
 
 Thanks to Frank J. T. Wojcik for helping with the documentation.
 
-Libpng version 1.6.25 - September 1, 2016:
+Libpng version 1.6.26 - October 20, 2016:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
 
@@ -6043,7 +6048,7 @@
 
 This code is released under the libpng license.
 
-libpng versions 1.0.7, July 1, 2000 through 1.6.25, September 1, 2016 are
+libpng versions 1.0.7, July 1, 2000 through 1.6.26, October 20, 2016 are
 Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
 derived from libpng-1.0.6, and are distributed according to the same
 disclaimer and license as libpng-1.0.6 with the following individuals
@@ -6168,7 +6173,7 @@
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-September 1, 2016
+October 20, 2016
 
 .\" end of man page
 
diff --git a/libpngpf.3 b/libpngpf.3
index 3d6eab5..ed37924 100644
--- a/libpngpf.3
+++ b/libpngpf.3
@@ -1,6 +1,6 @@
-.TH LIBPNGPF 3 "September 1, 2016"
+.TH LIBPNGPF 3 "October 20, 2016"
 .SH NAME
-libpng \- Portable Network Graphics (PNG) Reference Library 1.6.25
+libpng \- Portable Network Graphics (PNG) Reference Library 1.6.26
 (private functions)
 .SH SYNOPSIS
 \fB#include \fI"pngpriv.h"
diff --git a/mips/filter_msa_intrinsics.c b/mips/filter_msa_intrinsics.c
index 943bb3d..5930ae3 100644
--- a/mips/filter_msa_intrinsics.c
+++ b/mips/filter_msa_intrinsics.c
@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2016 Glenn Randers-Pehrson
  * Written by Mandar Sahastrabuddhe, August 2016.
- * Last changed in libpng 1.6.25 [September 1, 2016]
+ * Last changed in libpng 1.6.25 [October 20, 2016]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/mips/mips_init.c b/mips/mips_init.c
index 0bfb7a3..5bc79e6 100644
--- a/mips/mips_init.c
+++ b/mips/mips_init.c
@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2016 Glenn Randers-Pehrson
  * Written by Mandar Sahastrabuddhe, 2016.
- * Last changed in libpng 1.6.25 [September 1, 2016]
+ * Last changed in libpng 1.6.25 [October 20, 2016]
  *
  * This code is released under the libpng license.
  * For conditions of distribution and use, see the disclaimer
diff --git a/png.5 b/png.5
index 16d213c..bec6741 100644
--- a/png.5
+++ b/png.5
@@ -1,4 +1,4 @@
-.TH PNG 5 "September 1, 2016"
+.TH PNG 5 "October 20, 2016"
 .SH NAME
 png \- Portable Network Graphics (PNG) format
 .SH DESCRIPTION
diff --git a/png.c b/png.c
index 33e8c8f..6d5633c 100644
--- a/png.c
+++ b/png.c
@@ -1,7 +1,7 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.6.25 [September 1, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -14,7 +14,7 @@
 #include "pngpriv.h"
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_25 Your_png_h_is_not_version_1_6_25;
+typedef png_libpng_version_1_6_26 Your_png_h_is_not_version_1_6_26;
 
 /* Tells libpng that we have already handled the first "num_bytes" bytes
  * of the PNG file signature.  If the PNG data is embedded into another
@@ -458,7 +458,7 @@
 
 #ifdef PNG_TEXT_SUPPORTED
    /* Free text item num or (if num == -1) all text items */
-   if (info_ptr->text != 0 &&
+   if (info_ptr->text != NULL &&
        ((mask & PNG_FREE_TEXT) & info_ptr->free_me) != 0)
    {
       if (num != -1)
@@ -541,7 +541,7 @@
 
 #ifdef PNG_sPLT_SUPPORTED
    /* Free a given sPLT entry, or (if num == -1) all sPLT entries */
-   if (info_ptr->splt_palettes != 0 &&
+   if (info_ptr->splt_palettes != NULL &&
        ((mask & PNG_FREE_SPLT) & info_ptr->free_me) != 0)
    {
       if (num != -1)
@@ -571,7 +571,7 @@
 #endif
 
 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
-   if (info_ptr->unknown_chunks != 0 &&
+   if (info_ptr->unknown_chunks != NULL &&
        ((mask & PNG_FREE_UNKN) & info_ptr->free_me) != 0)
    {
       if (num != -1)
@@ -617,7 +617,7 @@
    /* Free any image bits attached to the info structure */
    if (((mask & PNG_FREE_ROWS) & info_ptr->free_me) != 0)
    {
-      if (info_ptr->row_pointers != 0)
+      if (info_ptr->row_pointers != NULL)
       {
          png_uint_32 row;
          for (row = 0; row < info_ptr->height; row++)
@@ -684,7 +684,7 @@
 void PNGAPI
 png_save_int_32(png_bytep buf, png_int_32 i)
 {
-   png_save_uint_32(buf, i);
+   png_save_uint_32(buf, (png_uint_32)i);
 }
 #  endif
 
@@ -775,14 +775,14 @@
 #else
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
-      "libpng version 1.6.25 - September 1, 2016" PNG_STRING_NEWLINE \
+      "libpng version 1.6.26 - October 20, 2016" PNG_STRING_NEWLINE \
       "Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson" \
       PNG_STRING_NEWLINE \
       "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
       "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
       PNG_STRING_NEWLINE;
 #  else
-   return "libpng version 1.6.25 - September 1, 2016\
+   return "libpng version 1.6.26 - October 20, 2016\
       Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
@@ -2529,7 +2529,7 @@
       error = 1;
    }
 
-   if (png_gt(((width + 7) & (~7)),
+   if (png_gt(((width + 7) & (~7U)),
        ((PNG_SIZE_MAX
            - 48        /* big_row_buf hack */
            - 1)        /* filter byte */
@@ -2940,7 +2940,7 @@
              */
             if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */
             {
-               czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */
+               czero = (unsigned int)(-exp_b10); /* PLUS 2 digits: TOTAL 3 */
                exp_b10 = 0;      /* Dot added below before first output. */
             }
             else
@@ -3118,11 +3118,11 @@
                if (exp_b10 < 0)
                {
                   *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */
-                  uexp_b10 = -exp_b10;
+                  uexp_b10 = (unsigned int)(-exp_b10);
                }
 
                else
-                  uexp_b10 = exp_b10;
+                  uexp_b10 = (unsigned int)exp_b10;
 
                cdigits = 0;
 
@@ -3184,9 +3184,9 @@
 
       /* Avoid overflow here on the minimum integer. */
       if (fp < 0)
-         *ascii++ = 45, num = -fp;
+         *ascii++ = 45, num = (png_uint_32)(-fp);
       else
-         num = fp;
+         num = (png_uint_32)fp;
 
       if (num <= 0x80000000) /* else overflowed */
       {
diff --git a/png.h b/png.h
index e1f59c3..f094463 100644
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.6.25, September 1, 2016
+ * libpng version 1.6.26, October 20, 2016
  *
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -12,7 +12,7 @@
  * Authors and maintainers:
  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *   libpng versions 0.89, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.6.25, September 1, 2016:
+ *   libpng versions 0.97, January 1998, through 1.6.26, October 20, 2016:
  *     Glenn Randers-Pehrson.
  *   See also "Contributing Authors", below.
  */
@@ -29,7 +29,7 @@
  * files that are distributed with libpng have other copyright owners and
  * are released under other open source licenses.
  *
- * libpng versions 1.0.7, July 1, 2000 through 1.6.25, September 1, 2016 are
+ * libpng versions 1.0.7, July 1, 2000 through 1.6.26, October 20, 2016 are
  * Copyright (c) 2000-2002, 2004, 2006-2016 Glenn Randers-Pehrson, are
  * derived from libpng-1.0.6, and are distributed according to the same
  * disclaimer and license as libpng-1.0.6 with the following individuals
@@ -218,7 +218,7 @@
  *    ...
  *    1.5.27                  15    10527  15.so.15.27[.0]
  *    ...
- *    1.6.25                  16    10625  16.so.16.25[.0]
+ *    1.6.26                  16    10626  16.so.16.26[.0]
  *
  *    Henceforth the source version will match the shared-library major
  *    and minor numbers; the shared-library major version number will be
@@ -246,13 +246,13 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    September 1, 2016
+ *    October 20, 2016
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
  *
  *    This is your unofficial assurance that libpng from version 0.71 and
- *    upward through 1.6.25 are Y2K compliant.  It is my belief that
+ *    upward through 1.6.26 are Y2K compliant.  It is my belief that
  *    earlier versions were also Y2K compliant.
  *
  *    Libpng only has two year fields.  One is a 2-byte unsigned integer
@@ -314,8 +314,8 @@
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "1.6.25"
-#define PNG_HEADER_VERSION_STRING " libpng version 1.6.25 - September 1, 2016\n"
+#define PNG_LIBPNG_VER_STRING "1.6.26"
+#define PNG_HEADER_VERSION_STRING " libpng version 1.6.26 - October 20, 2016\n"
 
 #define PNG_LIBPNG_VER_SONUM   16
 #define PNG_LIBPNG_VER_DLLNUM  16
@@ -323,7 +323,7 @@
 /* These should match the first 3 components of PNG_LIBPNG_VER_STRING: */
 #define PNG_LIBPNG_VER_MAJOR   1
 #define PNG_LIBPNG_VER_MINOR   6
-#define PNG_LIBPNG_VER_RELEASE 25
+#define PNG_LIBPNG_VER_RELEASE 26
 
 /* This should match the numeric part of the final component of
  * PNG_LIBPNG_VER_STRING, omitting any leading zero:
@@ -354,7 +354,7 @@
  * version 1.0.0 was mis-numbered 100 instead of 10000).  From
  * version 1.0.1 it's    xxyyzz, where x=major, y=minor, z=release
  */
-#define PNG_LIBPNG_VER 10625 /* 1.6.25 */
+#define PNG_LIBPNG_VER 10626 /* 1.6.26 */
 
 /* Library configuration: these options cannot be changed after
  * the library has been built.
@@ -464,7 +464,7 @@
 /* This triggers a compiler error in png.c, if png.c and png.h
  * do not agree upon the version number.
  */
-typedef char* png_libpng_version_1_6_25;
+typedef char* png_libpng_version_1_6_26;
 
 /* Basic control structions.  Read libpng-manual.txt or libpng.3 for more info.
  *
diff --git a/pngconf.h b/pngconf.h
index 08b4239..5c891eb 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -1,7 +1,7 @@
 
 /* pngconf.h - machine configurable file for libpng
  *
- * libpng version 1.6.25, September 1, 2016
+ * libpng version 1.6.26, October 20, 2016
  *
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@@ -507,9 +507,9 @@
 #  error "libpng requires a signed 32-bit (or more) type"
 #endif
 
-#if UINT_MAX > 4294967294
+#if UINT_MAX > 4294967294U
    typedef unsigned int png_uint_32;
-#elif ULONG_MAX > 4294967294
+#elif ULONG_MAX > 4294967294U
    typedef unsigned long int png_uint_32;
 #else
 #  error "libpng requires an unsigned 32-bit (or more) type"
diff --git a/pngerror.c b/pngerror.c
index f13b764..00d76f7 100644
--- a/pngerror.c
+++ b/pngerror.c
@@ -1,7 +1,7 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -573,7 +573,7 @@
 {
 #  define fixed_message "fixed point overflow in "
 #  define fixed_message_ln ((sizeof fixed_message)-1)
-   int  iin;
+   unsigned int  iin;
    char msg[fixed_message_ln+PNG_MAX_ERROR_TEXT];
    memcpy(msg, fixed_message, fixed_message_ln);
    iin = 0;
diff --git a/pngget.c b/pngget.c
index b3c6863..141c393 100644
--- a/pngget.c
+++ b/pngget.c
@@ -1,7 +1,7 @@
 
 /* pngget.c - retrieval of values from info struct
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -338,7 +338,7 @@
    png_fixed_point result;
    if (ppm <= PNG_UINT_31_MAX && png_muldiv(&result, (png_int_32)ppm, 127,
        5000) != 0)
-      return result;
+      return (png_uint_32)result;
 
    /* Overflow. */
    return 0;
diff --git a/pngmem.c b/pngmem.c
index 7053ec9..ff3ef7e 100644
--- a/pngmem.c
+++ b/pngmem.c
@@ -1,7 +1,7 @@
 
 /* pngmem.c - stub functions for memory allocation
  *
- * Last changed in libpng 1.6.24 [August 4, 2016%]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2014,2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -109,7 +109,7 @@
 png_malloc_array_checked(png_const_structrp png_ptr, int nelements,
     size_t element_size)
 {
-   png_alloc_size_t req = nelements; /* known to be > 0 */
+   png_alloc_size_t req = (png_alloc_size_t)nelements; /* known to be > 0 */
 
    if (req <= PNG_SIZE_MAX/element_size)
       return png_malloc_base(png_ptr, req * element_size);
diff --git a/pngpread.c b/pngpread.c
index 794352f..650ba1e 100644
--- a/pngpread.c
+++ b/pngpread.c
@@ -684,7 +684,12 @@
             png_warning(png_ptr, "Truncated compressed data in IDAT");
 
          else
-            png_error(png_ptr, "Decompression error in IDAT");
+         {
+            if (ret == Z_DATA_ERROR)
+               png_benign_error(png_ptr, "IDAT: ADLER32 checksum mismatch");
+            else
+               png_error(png_ptr, "Decompression error in IDAT");
+         }
 
          /* Skip the check on unprocessed input */
          return;
diff --git a/pngpriv.h b/pngpriv.h
index bed1cab..ed61165 100644
--- a/pngpriv.h
+++ b/pngpriv.h
@@ -1,7 +1,7 @@
 
 /* pngpriv.h - private declarations for use inside libpng
  *
- * Last changed in libpng 1.6.25 [September 1, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -533,7 +533,8 @@
 /* This implicitly assumes alignment is always to a power of 2. */
 #ifdef png_alignof
 #  define png_isaligned(ptr, type)\
-   ((((const char*)ptr-(const char*)0) & (png_alignof(type)-1)) == 0)
+   (((type)((const char*)ptr-(const char*)0) & \
+   (type)(png_alignof(type)-1)) == 0)
 #else
 #  define png_isaligned(ptr, type) 0
 #endif
@@ -550,92 +551,92 @@
  * are defined in png.h because they need to be visible to applications
  * that call png_set_unknown_chunk().
  */
-/* #define PNG_HAVE_IHDR            0x01 (defined in png.h) */
-/* #define PNG_HAVE_PLTE            0x02 (defined in png.h) */
-#define PNG_HAVE_IDAT               0x04
-/* #define PNG_AFTER_IDAT           0x08 (defined in png.h) */
-#define PNG_HAVE_IEND               0x10
-                   /*               0x20 (unused) */
-                   /*               0x40 (unused) */
-                   /*               0x80 (unused) */
-#define PNG_HAVE_CHUNK_HEADER      0x100
-#define PNG_WROTE_tIME             0x200
-#define PNG_WROTE_INFO_BEFORE_PLTE 0x400
-#define PNG_BACKGROUND_IS_GRAY     0x800
-#define PNG_HAVE_PNG_SIGNATURE    0x1000
-#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000 /* Have another chunk after IDAT */
-                   /*             0x4000 (unused) */
-#define PNG_IS_READ_STRUCT        0x8000 /* Else is a write struct */
+/* #define PNG_HAVE_IHDR            0x01U (defined in png.h) */
+/* #define PNG_HAVE_PLTE            0x02U (defined in png.h) */
+#define PNG_HAVE_IDAT               0x04U
+/* #define PNG_AFTER_IDAT           0x08U (defined in png.h) */
+#define PNG_HAVE_IEND               0x10U
+                   /*               0x20U (unused) */
+                   /*               0x40U (unused) */
+                   /*               0x80U (unused) */
+#define PNG_HAVE_CHUNK_HEADER      0x100U
+#define PNG_WROTE_tIME             0x200U
+#define PNG_WROTE_INFO_BEFORE_PLTE 0x400U
+#define PNG_BACKGROUND_IS_GRAY     0x800U
+#define PNG_HAVE_PNG_SIGNATURE    0x1000U
+#define PNG_HAVE_CHUNK_AFTER_IDAT 0x2000U /* Have another chunk after IDAT */
+                   /*             0x4000U (unused) */
+#define PNG_IS_READ_STRUCT        0x8000U /* Else is a write struct */
 
 /* Flags for the transformations the PNG library does on the image data */
-#define PNG_BGR                 0x0001
-#define PNG_INTERLACE           0x0002
-#define PNG_PACK                0x0004
-#define PNG_SHIFT               0x0008
-#define PNG_SWAP_BYTES          0x0010
-#define PNG_INVERT_MONO         0x0020
-#define PNG_QUANTIZE            0x0040
-#define PNG_COMPOSE             0x0080     /* Was PNG_BACKGROUND */
-#define PNG_BACKGROUND_EXPAND   0x0100
-#define PNG_EXPAND_16           0x0200     /* Added to libpng 1.5.2 */
-#define PNG_16_TO_8             0x0400     /* Becomes 'chop' in 1.5.4 */
-#define PNG_RGBA                0x0800
-#define PNG_EXPAND              0x1000
-#define PNG_GAMMA               0x2000
-#define PNG_GRAY_TO_RGB         0x4000
-#define PNG_FILLER              0x8000
-#define PNG_PACKSWAP           0x10000
-#define PNG_SWAP_ALPHA         0x20000
-#define PNG_STRIP_ALPHA        0x40000
-#define PNG_INVERT_ALPHA       0x80000
-#define PNG_USER_TRANSFORM    0x100000
-#define PNG_RGB_TO_GRAY_ERR   0x200000
-#define PNG_RGB_TO_GRAY_WARN  0x400000
-#define PNG_RGB_TO_GRAY       0x600000 /* two bits, RGB_TO_GRAY_ERR|WARN */
-#define PNG_ENCODE_ALPHA      0x800000 /* Added to libpng-1.5.4 */
-#define PNG_ADD_ALPHA        0x1000000 /* Added to libpng-1.2.7 */
-#define PNG_EXPAND_tRNS      0x2000000 /* Added to libpng-1.2.9 */
-#define PNG_SCALE_16_TO_8    0x4000000 /* Added to libpng-1.5.4 */
-                       /*    0x8000000 unused */
-                       /*   0x10000000 unused */
-                       /*   0x20000000 unused */
-                       /*   0x40000000 unused */
+#define PNG_BGR                 0x0001U
+#define PNG_INTERLACE           0x0002U
+#define PNG_PACK                0x0004U
+#define PNG_SHIFT               0x0008U
+#define PNG_SWAP_BYTES          0x0010U
+#define PNG_INVERT_MONO         0x0020U
+#define PNG_QUANTIZE            0x0040U
+#define PNG_COMPOSE             0x0080U    /* Was PNG_BACKGROUND */
+#define PNG_BACKGROUND_EXPAND   0x0100U
+#define PNG_EXPAND_16           0x0200U    /* Added to libpng 1.5.2 */
+#define PNG_16_TO_8             0x0400U    /* Becomes 'chop' in 1.5.4 */
+#define PNG_RGBA                0x0800U
+#define PNG_EXPAND              0x1000U
+#define PNG_GAMMA               0x2000U
+#define PNG_GRAY_TO_RGB         0x4000U
+#define PNG_FILLER              0x8000U
+#define PNG_PACKSWAP           0x10000U
+#define PNG_SWAP_ALPHA         0x20000U
+#define PNG_STRIP_ALPHA        0x40000U
+#define PNG_INVERT_ALPHA       0x80000U
+#define PNG_USER_TRANSFORM    0x100000U
+#define PNG_RGB_TO_GRAY_ERR   0x200000U
+#define PNG_RGB_TO_GRAY_WARN  0x400000U
+#define PNG_RGB_TO_GRAY       0x600000U /* two bits, RGB_TO_GRAY_ERR|WARN */
+#define PNG_ENCODE_ALPHA      0x800000U /* Added to libpng-1.5.4 */
+#define PNG_ADD_ALPHA        0x1000000U /* Added to libpng-1.2.7 */
+#define PNG_EXPAND_tRNS      0x2000000U /* Added to libpng-1.2.9 */
+#define PNG_SCALE_16_TO_8    0x4000000U /* Added to libpng-1.5.4 */
+                       /*    0x8000000U unused */
+                       /*   0x10000000U unused */
+                       /*   0x20000000U unused */
+                       /*   0x40000000U unused */
 /* Flags for png_create_struct */
-#define PNG_STRUCT_PNG   0x0001
-#define PNG_STRUCT_INFO  0x0002
+#define PNG_STRUCT_PNG   0x0001U
+#define PNG_STRUCT_INFO  0x0002U
 
 /* Flags for the png_ptr->flags rather than declaring a byte for each one */
-#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001
-#define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002 /* Added to libpng-1.6.0 */
-                                  /*      0x0004    unused */
-#define PNG_FLAG_ZSTREAM_ENDED            0x0008 /* Added to libpng-1.6.0 */
-                                  /*      0x0010    unused */
-                                  /*      0x0020    unused */
-#define PNG_FLAG_ROW_INIT                 0x0040
-#define PNG_FLAG_FILLER_AFTER             0x0080
-#define PNG_FLAG_CRC_ANCILLARY_USE        0x0100
-#define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200
-#define PNG_FLAG_CRC_CRITICAL_USE         0x0400
-#define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800
-#define PNG_FLAG_ASSUME_sRGB              0x1000 /* Added to libpng-1.5.4 */
-#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000 /* Added to libpng-1.5.4 */
-#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000 /* Added to libpng-1.5.4 */
-/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000 */
-/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000 */
-#define PNG_FLAG_LIBRARY_MISMATCH        0x20000
-#define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000
-#define PNG_FLAG_STRIP_ERROR_TEXT        0x80000
-#define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000 /* Added to libpng-1.4.0 */
-#define PNG_FLAG_APP_WARNINGS_WARN      0x200000 /* Added to libpng-1.6.0 */
-#define PNG_FLAG_APP_ERRORS_WARN        0x400000 /* Added to libpng-1.6.0 */
-                                  /*    0x800000    unused */
-                                  /*   0x1000000    unused */
-                                  /*   0x2000000    unused */
-                                  /*   0x4000000    unused */
-                                  /*   0x8000000    unused */
-                                  /*  0x10000000    unused */
-                                  /*  0x20000000    unused */
-                                  /*  0x40000000    unused */
+#define PNG_FLAG_ZLIB_CUSTOM_STRATEGY     0x0001U
+#define PNG_FLAG_ZSTREAM_INITIALIZED      0x0002U /* Added to libpng-1.6.0 */
+                                  /*      0x0004U    unused */
+#define PNG_FLAG_ZSTREAM_ENDED            0x0008U /* Added to libpng-1.6.0 */
+                                  /*      0x0010U    unused */
+                                  /*      0x0020U    unused */
+#define PNG_FLAG_ROW_INIT                 0x0040U
+#define PNG_FLAG_FILLER_AFTER             0x0080U
+#define PNG_FLAG_CRC_ANCILLARY_USE        0x0100U
+#define PNG_FLAG_CRC_ANCILLARY_NOWARN     0x0200U
+#define PNG_FLAG_CRC_CRITICAL_USE         0x0400U
+#define PNG_FLAG_CRC_CRITICAL_IGNORE      0x0800U
+#define PNG_FLAG_ASSUME_sRGB              0x1000U /* Added to libpng-1.5.4 */
+#define PNG_FLAG_OPTIMIZE_ALPHA           0x2000U /* Added to libpng-1.5.4 */
+#define PNG_FLAG_DETECT_UNINITIALIZED     0x4000U /* Added to libpng-1.5.4 */
+/* #define PNG_FLAG_KEEP_UNKNOWN_CHUNKS      0x8000U */
+/* #define PNG_FLAG_KEEP_UNSAFE_CHUNKS      0x10000U */
+#define PNG_FLAG_LIBRARY_MISMATCH        0x20000U
+#define PNG_FLAG_STRIP_ERROR_NUMBERS     0x40000U
+#define PNG_FLAG_STRIP_ERROR_TEXT        0x80000U
+#define PNG_FLAG_BENIGN_ERRORS_WARN     0x100000U /* Added to libpng-1.4.0 */
+#define PNG_FLAG_APP_WARNINGS_WARN      0x200000U /* Added to libpng-1.6.0 */
+#define PNG_FLAG_APP_ERRORS_WARN        0x400000U /* Added to libpng-1.6.0 */
+                                  /*    0x800000U    unused */
+                                  /*   0x1000000U    unused */
+                                  /*   0x2000000U    unused */
+                                  /*   0x4000000U    unused */
+                                  /*   0x8000000U    unused */
+                                  /*  0x10000000U    unused */
+                                  /*  0x20000000U    unused */
+                                  /*  0x40000000U    unused */
 
 #define PNG_FLAG_CRC_ANCILLARY_MASK (PNG_FLAG_CRC_ANCILLARY_USE | \
                                      PNG_FLAG_CRC_ANCILLARY_NOWARN)
@@ -669,6 +670,24 @@
     ((png_size_t)(width) * (((png_size_t)(pixel_bits)) >> 3)) : \
     (( ((png_size_t)(width) * ((png_size_t)(pixel_bits))) + 7) >> 3) )
 
+/* This returns the number of trailing bits in the last byte of a row, 0 if the
+ * last byte is completely full of pixels.  It is, in principle, (pixel_bits x
+ * width) % 8, but that would overflow for large 'width'.  The second macro is
+ * the same except that it returns the number of unused bits in the last byte;
+ * (8-TRAILBITS), but 0 when TRAILBITS is 0.
+ *
+ * NOTE: these macros are intended to be self-evidently correct and never
+ * overflow on the assumption that pixel_bits is in the range 0..255.  The
+ * arguments are evaluated only once and they can be signed (e.g. as a result of
+ * the integral promotions).  The result of the expression always has type
+ * (png_uint_32), however the compiler always knows it is in the range 0..7.
+ */
+#define PNG_TRAILBITS(pixel_bits, width) \
+    (((pixel_bits) * ((width) % (png_uint_32)8)) % 8)
+
+#define PNG_PADBITS(pixel_bits, width) \
+    ((8 - PNG_TRAILBITS(pixel_bits, width)) % 8)
+
 /* PNG_OUT_OF_RANGE returns true if value is outside the range
  * ideal-delta..ideal+delta.  Each argument is evaluated twice.
  * "ideal" and "delta" should be constants, normally simple
@@ -1263,7 +1282,7 @@
 /* Initialize the row buffers, etc. */
 PNG_INTERNAL_FUNCTION(void,png_read_start_row,(png_structrp png_ptr),PNG_EMPTY);
 
-#if PNG_ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1240
 PNG_INTERNAL_FUNCTION(int,png_zlib_inflate,(png_structrp png_ptr, int flush),
       PNG_EMPTY);
 #  define PNG_INFLATE(pp, flush) png_zlib_inflate(pp, flush)
diff --git a/pngread.c b/pngread.c
index 1000326..106a805 100644
--- a/pngread.c
+++ b/pngread.c
@@ -1,7 +1,7 @@
 
 /* pngread.c - read a PNG file
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -359,9 +359,9 @@
 
          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
          {
-            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
-            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
-            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
+            png_uint_32 s0   = (png_uint_32)(*(rp    ) << 8) | *(rp + 1);
+            png_uint_32 s1   = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
+            png_uint_32 s2   = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
             png_uint_32 red  = (s0 + s1 + 65536) & 0xffff;
             png_uint_32 blue = (s2 + s1 + 65536) & 0xffff;
             *(rp    ) = (png_byte)((red >> 8) & 0xff);
@@ -1393,7 +1393,9 @@
    png_structrp png_ptr = image->opaque->png_ptr;
    png_inforp info_ptr = image->opaque->info_ptr;
 
+#ifdef PNG_BENIGN_ERRORS_SUPPORTED
    png_set_benign_errors(png_ptr, 1/*warn*/);
+#endif
    png_read_info(png_ptr, info_ptr);
 
    /* Do this the fast way; just read directly out of png_struct. */
@@ -1431,7 +1433,7 @@
             break;
 
          case PNG_COLOR_TYPE_PALETTE:
-            cmap_entries = png_ptr->num_palette;
+            cmap_entries = (png_uint_32)png_ptr->num_palette;
             break;
 
          default:
@@ -1966,7 +1968,7 @@
    for (i=0; i<256; ++i)
       png_create_colormap_entry(display, i, i, i, i, 255, P_FILE);
 
-   return i;
+   return (int)i;
 }
 
 static int
@@ -1977,7 +1979,7 @@
    for (i=0; i<256; ++i)
       png_create_colormap_entry(display, i, i, i, i, 255, P_sRGB);
 
-   return i;
+   return (int)i;
 }
 #define PNG_GRAY_COLORMAP_ENTRIES 256
 
@@ -2031,7 +2033,7 @@
              P_sRGB);
    }
 
-   return i;
+   return (int)i;
 }
 
 #define PNG_GA_COLORMAP_ENTRIES 256
@@ -2056,7 +2058,7 @@
       }
    }
 
-   return i;
+   return (int)i;
 }
 
 #define PNG_RGB_COLORMAP_ENTRIES 216
@@ -2249,7 +2251,7 @@
             if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
                png_error(png_ptr, "gray[16] color-map: too few entries");
 
-            cmap_entries = make_gray_colormap(display);
+            cmap_entries = (unsigned int)make_gray_colormap(display);
 
             if (png_ptr->num_trans > 0)
             {
@@ -2347,7 +2349,7 @@
             if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
                png_error(png_ptr, "gray+alpha color-map: too few entries");
 
-            cmap_entries = make_ga_colormap(display);
+            cmap_entries = (unsigned int)make_ga_colormap(display);
 
             background_index = PNG_CMAP_GA_BACKGROUND;
             output_processing = PNG_CMAP_GA;
@@ -2381,7 +2383,7 @@
                if (PNG_GRAY_COLORMAP_ENTRIES > image->colormap_entries)
                   png_error(png_ptr, "gray-alpha color-map: too few entries");
 
-               cmap_entries = make_gray_colormap(display);
+               cmap_entries = (unsigned int)make_gray_colormap(display);
 
                if (output_encoding == P_LINEAR)
                {
@@ -2520,7 +2522,7 @@
                if (PNG_GA_COLORMAP_ENTRIES > image->colormap_entries)
                   png_error(png_ptr, "rgb[ga] color-map: too few entries");
 
-               cmap_entries = make_ga_colormap(display);
+               cmap_entries = (unsigned int)make_ga_colormap(display);
                background_index = PNG_CMAP_GA_BACKGROUND;
                output_processing = PNG_CMAP_GA;
             }
@@ -2546,12 +2548,12 @@
                   png_ptr->num_trans > 0) &&
                   png_gamma_not_sRGB(png_ptr->colorspace.gamma) != 0)
                {
-                  cmap_entries = make_gray_file_colormap(display);
+                  cmap_entries = (unsigned int)make_gray_file_colormap(display);
                   data_encoding = P_FILE;
                }
 
                else
-                  cmap_entries = make_gray_colormap(display);
+                  cmap_entries = (unsigned int)make_gray_colormap(display);
 
                /* But if the input has alpha or transparency it must be removed
                 */
@@ -2639,7 +2641,7 @@
                   if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
                      png_error(png_ptr, "rgb+alpha color-map: too few entries");
 
-                  cmap_entries = make_rgb_colormap(display);
+                  cmap_entries = (unsigned int)make_rgb_colormap(display);
 
                   /* Add a transparent entry. */
                   png_create_colormap_entry(display, cmap_entries, 255, 255,
@@ -2688,7 +2690,7 @@
                   if (PNG_RGB_COLORMAP_ENTRIES+1+27 > image->colormap_entries)
                      png_error(png_ptr, "rgb-alpha color-map: too few entries");
 
-                  cmap_entries = make_rgb_colormap(display);
+                  cmap_entries = (unsigned int)make_rgb_colormap(display);
 
                   png_create_colormap_entry(display, cmap_entries, back_r,
                       back_g, back_b, 0/*unused*/, output_encoding);
@@ -2773,7 +2775,7 @@
                if (PNG_RGB_COLORMAP_ENTRIES > image->colormap_entries)
                   png_error(png_ptr, "rgb color-map: too few entries");
 
-               cmap_entries = make_rgb_colormap(display);
+               cmap_entries = (unsigned int)make_rgb_colormap(display);
                output_processing = PNG_CMAP_RGB;
             }
          }
@@ -2797,11 +2799,11 @@
 
             output_processing = PNG_CMAP_NONE;
             data_encoding = P_FILE; /* Don't change from color-map indices */
-            cmap_entries = png_ptr->num_palette;
+            cmap_entries = (unsigned int)png_ptr->num_palette;
             if (cmap_entries > 256)
                cmap_entries = 256;
 
-            if (cmap_entries > image->colormap_entries)
+            if (cmap_entries > (unsigned int)image->colormap_entries)
                png_error(png_ptr, "palette color-map: too few entries");
 
             for (i=0; i < cmap_entries; ++i)
@@ -2913,7 +2915,7 @@
          png_error(png_ptr, "bad background index (internal error)");
    }
 
-   display->colormap_processing = output_processing;
+   display->colormap_processing = (int)output_processing;
 
    return 1/*ok*/;
 }
@@ -3222,14 +3224,14 @@
 
    else
    {
-      png_alloc_size_t row_bytes = display->row_bytes;
+      png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
 
       while (--passes >= 0)
       {
          png_uint_32      y = image->height;
          png_bytep        row = png_voidcast(png_bytep, display->first_row);
 
-         while (y-- > 0)
+         for (; y > 0; --y)
          {
             png_read_row(png_ptr, row, NULL);
             row += row_bytes;
@@ -3557,8 +3559,9 @@
              * stride which was multiplied by 2 (below) to get row_bytes.
              */
             ptrdiff_t    step_row = display->row_bytes / 2;
-            int preserve_alpha = (image->format & PNG_FORMAT_FLAG_ALPHA) != 0;
-            unsigned int outchannels = 1+preserve_alpha;
+            unsigned int preserve_alpha = (image->format &
+                PNG_FORMAT_FLAG_ALPHA) != 0;
+            unsigned int outchannels = 1U+preserve_alpha;
             int swap_alpha = 0;
 
 #           ifdef PNG_SIMPLIFIED_READ_AFIRST_SUPPORTED
@@ -4055,14 +4058,14 @@
 
    else
    {
-      png_alloc_size_t row_bytes = display->row_bytes;
+      png_alloc_size_t row_bytes = (png_alloc_size_t)display->row_bytes;
 
       while (--passes >= 0)
       {
          png_uint_32      y = image->height;
          png_bytep        row = png_voidcast(png_bytep, display->first_row);
 
-         while (y-- > 0)
+         for (; y > 0; --y)
          {
             png_read_row(png_ptr, row, NULL);
             row += row_bytes;
@@ -4091,7 +4094,7 @@
        * bits; this is just to verify that the 'row_stride' argument can be
        * represented.
        */
-      if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
+      if (image->width <= 0x7fffffffU/channels) /* no overflow */
       {
          png_uint_32 check;
          const png_uint_32 png_row_stride = image->width * channels;
@@ -4100,10 +4103,10 @@
             row_stride = (png_int_32)/*SAFE*/png_row_stride;
 
          if (row_stride < 0)
-            check = -row_stride;
+            check = (png_uint_32)(-row_stride);
 
          else
-            check = row_stride;
+            check = (png_uint_32)row_stride;
 
          /* This verifies 'check', the absolute value of the actual stride
           * passed in and detects overflow in the application calculation (i.e.
@@ -4128,7 +4131,7 @@
              * accomodated on 64-bit systems.
              */
             if (image->height <=
-                0xFFFFFFFFU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
+                0xffffffffU/PNG_IMAGE_PIXEL_COMPONENT_SIZE(image->format)/check)
             {
                if ((image->format & PNG_FORMAT_FLAG_COLORMAP) == 0 ||
                   (image->colormap_entries > 0 && colormap != NULL))
diff --git a/pngrtran.c b/pngrtran.c
index 748ffb3..0b4f4f9 100644
--- a/pngrtran.c
+++ b/pngrtran.c
@@ -429,7 +429,7 @@
       int i;
 
       png_ptr->quantize_index = (png_bytep)png_malloc(png_ptr,
-          (png_uint_32)(num_palette * (sizeof (png_byte))));
+          (png_uint_32)((png_uint_32)num_palette * (sizeof (png_byte))));
       for (i = 0; i < num_palette; i++)
          png_ptr->quantize_index[i] = (png_byte)i;
    }
@@ -446,7 +446,7 @@
 
          /* Initialize an array to sort colors */
          png_ptr->quantize_sort = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * (sizeof (png_byte))));
+             (png_uint_32)((png_uint_32)num_palette * (sizeof (png_byte))));
 
          /* Initialize the quantize_sort array */
          for (i = 0; i < num_palette; i++)
@@ -580,9 +580,9 @@
 
          /* Initialize palette index arrays */
          png_ptr->index_to_palette = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * (sizeof (png_byte))));
+             (png_uint_32)((png_uint_32)num_palette * (sizeof (png_byte))));
          png_ptr->palette_to_index = (png_bytep)png_malloc(png_ptr,
-             (png_uint_32)(num_palette * (sizeof (png_byte))));
+             (png_uint_32)((png_uint_32)num_palette * (sizeof (png_byte))));
 
          /* Initialize the sort array */
          for (i = 0; i < num_palette; i++)
@@ -2150,7 +2150,7 @@
          {
             png_bytep sp = row + (png_size_t)((row_width - 1) >> 3);
             png_bytep dp = row + (png_size_t)row_width - 1;
-            png_uint_32 shift = 7 - (int)((row_width + 7) & 0x07);
+            png_uint_32 shift = 7U - ((row_width + 7U) & 0x07);
             for (i = 0; i < row_width; i++)
             {
                *dp = (png_byte)((*sp >> shift) & 0x01);
@@ -2174,7 +2174,7 @@
 
             png_bytep sp = row + (png_size_t)((row_width - 1) >> 2);
             png_bytep dp = row + (png_size_t)row_width - 1;
-            png_uint_32 shift = (int)((3 - ((row_width + 3) & 0x03)) << 1);
+            png_uint_32 shift = ((3U - ((row_width + 3U) & 0x03)) << 1);
             for (i = 0; i < row_width; i++)
             {
                *dp = (png_byte)((*sp >> shift) & 0x03);
@@ -2197,7 +2197,7 @@
          {
             png_bytep sp = row + (png_size_t)((row_width - 1) >> 1);
             png_bytep dp = row + (png_size_t)row_width - 1;
-            png_uint_32 shift = (int)((1 - ((row_width + 1) & 0x01)) << 2);
+            png_uint_32 shift = ((1U - ((row_width + 1U) & 0x01)) << 2);
             for (i = 0; i < row_width; i++)
             {
                *dp = (png_byte)((*sp >> shift) & 0x0f);
@@ -3223,7 +3223,8 @@
                         == png_ptr->trans_color.gray)
                      {
                         unsigned int tmp = *sp & (0x7f7f >> (7 - shift));
-                        tmp |= png_ptr->background.gray << shift;
+                        tmp |=
+                            (unsigned int)(png_ptr->background.gray << shift);
                         *sp = (png_byte)(tmp & 0xff);
                      }
 
@@ -3252,7 +3253,8 @@
                             == png_ptr->trans_color.gray)
                         {
                            unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
-                           tmp |= png_ptr->background.gray << shift;
+                           tmp |=
+                              (unsigned int)png_ptr->background.gray << shift;
                            *sp = (png_byte)(tmp & 0xff);
                         }
 
@@ -3262,7 +3264,7 @@
                            unsigned int g = (gamma_table [p | (p << 2) |
                                (p << 4) | (p << 6)] >> 6) & 0x03;
                            unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
-                           tmp |= g << shift;
+                           tmp |= (unsigned int)(g << shift);
                            *sp = (png_byte)(tmp & 0xff);
                         }
 
@@ -3288,7 +3290,8 @@
                             == png_ptr->trans_color.gray)
                         {
                            unsigned int tmp = *sp & (0x3f3f >> (6 - shift));
-                           tmp |= png_ptr->background.gray << shift;
+                           tmp |=
+                               (unsigned int)png_ptr->background.gray << shift;
                            *sp = (png_byte)(tmp & 0xff);
                         }
 
@@ -3318,7 +3321,8 @@
                             == png_ptr->trans_color.gray)
                         {
                            unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
-                           tmp |= png_ptr->background.gray << shift;
+                           tmp |= 
+                              (unsigned int)(png_ptr->background.gray << shift);
                            *sp = (png_byte)(tmp & 0xff);
                         }
 
@@ -3328,7 +3332,7 @@
                            unsigned int g = (gamma_table[p | (p << 4)] >> 4) &
                               0x0f;
                            unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
-                           tmp |= g << shift;
+                           tmp |= (unsigned int)(g << shift);
                            *sp = (png_byte)(tmp & 0xff);
                         }
 
@@ -3354,7 +3358,8 @@
                             == png_ptr->trans_color.gray)
                         {
                            unsigned int tmp = *sp & (0x0f0f >> (4 - shift));
-                           tmp |= png_ptr->background.gray << shift;
+                           tmp |=
+                              (unsigned int)(png_ptr->background.gray << shift);
                            *sp = (png_byte)(tmp & 0xff);
                         }
 
diff --git a/pngrutil.c b/pngrutil.c
index 3eaa635..fb5f5f0 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -1,7 +1,7 @@
 
 /* pngrutil.c - utilities to read a PNG file
  *
- * Last changed in libpng 1.6.25 [September 1, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -86,7 +86,7 @@
 {
    png_uint_32 uval = png_get_uint_32(buf);
    if ((uval & 0x80000000) == 0) /* non-negative */
-      return uval;
+      return (png_int_32)uval;
 
    uval = (uval ^ 0xffffffff) + 1;  /* 2's complement: -x = ~x+1 */
    if ((uval & 0x80000000) == 0) /* no overflow */
@@ -370,11 +370,10 @@
     */
    {
       int ret; /* zlib return code */
-#if PNG_ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1240
+      int window_bits = 0;
 
 # if defined(PNG_SET_OPTION_SUPPORTED) && defined(PNG_MAXIMUM_INFLATE_WINDOW)
-      int window_bits;
-
       if (((png_ptr->options >> PNG_MAXIMUM_INFLATE_WINDOW) & 3) ==
           PNG_OPTION_ON)
       {
@@ -384,13 +383,11 @@
 
       else
       {
-         window_bits = 0;
          png_ptr->zstream_start = 1;
       }
-# else
-#   define window_bits 0
 # endif
-#endif
+
+#endif /* ZLIB_VERNUM >= 0x1240 */
 
       /* Set this for safety, just in case the previous owner left pointers to
        * memory allocations.
@@ -402,25 +399,31 @@
 
       if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
       {
-#if PNG_ZLIB_VERNUM < 0x1240
-         ret = inflateReset(&png_ptr->zstream);
-#else
+#if ZLIB_VERNUM >= 0x1240
          ret = inflateReset2(&png_ptr->zstream, window_bits);
+#else
+         ret = inflateReset(&png_ptr->zstream);
 #endif
       }
 
       else
       {
-#if PNG_ZLIB_VERNUM < 0x1240
-         ret = inflateInit(&png_ptr->zstream);
-#else
+#if ZLIB_VERNUM >= 0x1240
          ret = inflateInit2(&png_ptr->zstream, window_bits);
+#else
+         ret = inflateInit(&png_ptr->zstream);
 #endif
 
          if (ret == Z_OK)
             png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
       }
 
+#if ZLIB_VERNUM >= 0x1281
+      /* Turn off validation of the ADLER32 checksum */
+      if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
+         ret = inflateValidate(&png_ptr->zstream, 0);
+#endif
+
       if (ret == Z_OK)
          png_ptr->zowner = owner;
 
@@ -435,7 +438,7 @@
 #endif
 }
 
-#if PNG_ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1240
 /* Handle the start of the inflate stream if we called inflateInit2(strm,0);
  * in this case some zlib versions skip validation of the CINFO field and, in
  * certain circumstances, libpng may end up displaying an invalid image, in
@@ -1011,7 +1014,7 @@
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
 #endif
    {
-      png_crc_finish(png_ptr, (int) length - num * 3);
+      png_crc_finish(png_ptr, (png_uint_32) (length - (unsigned int)num * 3));
    }
 
 #ifndef PNG_READ_OPT_PLTE_SUPPORTED
@@ -1717,13 +1720,13 @@
    data_length = length - (png_uint_32)(entry_start - buffer);
 
    /* Integrity-check the data length */
-   if ((data_length % entry_size) != 0)
+   if ((data_length % (unsigned int)entry_size) != 0)
    {
       png_warning(png_ptr, "sPLT chunk has bad length");
       return;
    }
 
-   dl = (png_int_32)(data_length / entry_size);
+   dl = (png_uint_32)(data_length / (unsigned int)entry_size);
    max_dl = PNG_SIZE_MAX / (sizeof (png_sPLT_entry));
 
    if (dl > max_dl)
@@ -1732,10 +1735,10 @@
       return;
    }
 
-   new_palette.nentries = (png_int_32)(data_length / entry_size);
+   new_palette.nentries = (png_int_32)(data_length / (unsigned int)entry_size);
 
-   new_palette.entries = (png_sPLT_entryp)png_malloc_warn(
-       png_ptr, new_palette.nentries * (sizeof (png_sPLT_entry)));
+   new_palette.entries = (png_sPLT_entryp)png_malloc_warn(png_ptr,
+       (png_alloc_size_t) new_palette.nentries * (sizeof (png_sPLT_entry)));
 
    if (new_palette.entries == NULL)
    {
@@ -3099,7 +3102,7 @@
 #     ifdef PNG_READ_PACKSWAP_SUPPORTED
       if ((png_ptr->transformations & PNG_PACKSWAP) != 0)
          /* little-endian byte */
-         end_mask = 0xff << end_mask;
+         end_mask = (unsigned int)(0xff << end_mask);
 
       else /* big-endian byte */
 #     endif
@@ -3545,7 +3548,7 @@
 {
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */
    /* Offset to next interlace block */
-   static PNG_CONST int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
+   static PNG_CONST unsigned int png_pass_inc[7] = {8, 8, 4, 4, 2, 2, 1};
 
    png_debug(1, "in png_do_read_interlace");
    if (row != NULL && row_info != NULL)
@@ -3560,9 +3563,10 @@
          {
             png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 3);
             png_bytep dp = row + (png_size_t)((final_width - 1) >> 3);
-            int sshift, dshift;
-            int s_start, s_end, s_inc;
-            int jstop = png_pass_inc[pass];
+            unsigned int sshift, dshift;
+            unsigned int s_start, s_end;
+            int s_inc;
+            int jstop = (int)png_pass_inc[pass];
             png_byte v;
             png_uint_32 i;
             int j;
@@ -3570,8 +3574,8 @@
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
             if ((transformations & PNG_PACKSWAP) != 0)
             {
-                sshift = (int)((row_info->width + 7) & 0x07);
-                dshift = (int)((final_width + 7) & 0x07);
+                sshift = ((row_info->width + 7) & 0x07);
+                dshift = ((final_width + 7) & 0x07);
                 s_start = 7;
                 s_end = 0;
                 s_inc = -1;
@@ -3580,8 +3584,8 @@
             else
 #endif
             {
-                sshift = 7 - (int)((row_info->width + 7) & 0x07);
-                dshift = 7 - (int)((final_width + 7) & 0x07);
+                sshift = 7 - ((row_info->width + 7) & 0x07);
+                dshift = 7 - ((final_width + 7) & 0x07);
                 s_start = 0;
                 s_end = 7;
                 s_inc = 1;
@@ -3593,7 +3597,7 @@
                for (j = 0; j < jstop; j++)
                {
                   unsigned int tmp = *dp & (0x7f7f >> (7 - dshift));
-                  tmp |= v << dshift;
+                  tmp |= (unsigned int)(v << dshift);
                   *dp = (png_byte)(tmp & 0xff);
 
                   if (dshift == s_end)
@@ -3603,7 +3607,7 @@
                   }
 
                   else
-                     dshift += s_inc;
+                     dshift = (unsigned int)((int)dshift + s_inc);
                }
 
                if (sshift == s_end)
@@ -3613,7 +3617,7 @@
                }
 
                else
-                  sshift += s_inc;
+                  sshift = (unsigned int)((int)sshift + s_inc);
             }
             break;
          }
@@ -3622,16 +3626,17 @@
          {
             png_bytep sp = row + (png_uint_32)((row_info->width - 1) >> 2);
             png_bytep dp = row + (png_uint_32)((final_width - 1) >> 2);
-            int sshift, dshift;
-            int s_start, s_end, s_inc;
-            int jstop = png_pass_inc[pass];
+            unsigned int sshift, dshift;
+            unsigned int s_start, s_end;
+            int s_inc;
+            int jstop = (int)png_pass_inc[pass];
             png_uint_32 i;
 
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
             if ((transformations & PNG_PACKSWAP) != 0)
             {
-               sshift = (int)(((row_info->width + 3) & 0x03) << 1);
-               dshift = (int)(((final_width + 3) & 0x03) << 1);
+               sshift = (((row_info->width + 3) & 0x03) << 1);
+               dshift = (((final_width + 3) & 0x03) << 1);
                s_start = 6;
                s_end = 0;
                s_inc = -2;
@@ -3640,8 +3645,8 @@
             else
 #endif
             {
-               sshift = (int)((3 - ((row_info->width + 3) & 0x03)) << 1);
-               dshift = (int)((3 - ((final_width + 3) & 0x03)) << 1);
+               sshift = ((3 - ((row_info->width + 3) & 0x03)) << 1);
+               dshift = ((3 - ((final_width + 3) & 0x03)) << 1);
                s_start = 0;
                s_end = 6;
                s_inc = 2;
@@ -3656,7 +3661,7 @@
                for (j = 0; j < jstop; j++)
                {
                   unsigned int tmp = *dp & (0x3f3f >> (6 - dshift));
-                  tmp |= v << dshift;
+                  tmp |= (unsigned int)(v << dshift);
                   *dp = (png_byte)(tmp & 0xff);
 
                   if (dshift == s_end)
@@ -3666,7 +3671,7 @@
                   }
 
                   else
-                     dshift += s_inc;
+                     dshift = (unsigned int)((int)dshift + s_inc);
                }
 
                if (sshift == s_end)
@@ -3676,7 +3681,7 @@
                }
 
                else
-                  sshift += s_inc;
+                  sshift = (unsigned int)((int)sshift + s_inc);
             }
             break;
          }
@@ -3685,16 +3690,17 @@
          {
             png_bytep sp = row + (png_size_t)((row_info->width - 1) >> 1);
             png_bytep dp = row + (png_size_t)((final_width - 1) >> 1);
-            int sshift, dshift;
-            int s_start, s_end, s_inc;
+            unsigned int sshift, dshift;
+            unsigned int s_start, s_end;
+            int s_inc;
             png_uint_32 i;
-            int jstop = png_pass_inc[pass];
+            int jstop = (int)png_pass_inc[pass];
 
 #ifdef PNG_READ_PACKSWAP_SUPPORTED
             if ((transformations & PNG_PACKSWAP) != 0)
             {
-               sshift = (int)(((row_info->width + 1) & 0x01) << 2);
-               dshift = (int)(((final_width + 1) & 0x01) << 2);
+               sshift = (((row_info->width + 1) & 0x01) << 2);
+               dshift = (((final_width + 1) & 0x01) << 2);
                s_start = 4;
                s_end = 0;
                s_inc = -4;
@@ -3703,8 +3709,8 @@
             else
 #endif
             {
-               sshift = (int)((1 - ((row_info->width + 1) & 0x01)) << 2);
-               dshift = (int)((1 - ((final_width + 1) & 0x01)) << 2);
+               sshift = ((1 - ((row_info->width + 1) & 0x01)) << 2);
+               dshift = ((1 - ((final_width + 1) & 0x01)) << 2);
                s_start = 0;
                s_end = 4;
                s_inc = 4;
@@ -3718,7 +3724,7 @@
                for (j = 0; j < jstop; j++)
                {
                   unsigned int tmp = *dp & (0xf0f >> (4 - dshift));
-                  tmp |= v << dshift;
+                  tmp |= (unsigned int)(v << dshift);
                   *dp = (png_byte)(tmp & 0xff);
 
                   if (dshift == s_end)
@@ -3728,7 +3734,7 @@
                   }
 
                   else
-                     dshift += s_inc;
+                     dshift = (unsigned int)((int)dshift + s_inc);
                }
 
                if (sshift == s_end)
@@ -3738,7 +3744,7 @@
                }
 
                else
-                  sshift += s_inc;
+                  sshift = (unsigned int)((int)sshift + s_inc);
             }
             break;
          }
@@ -3752,7 +3758,7 @@
 
             png_bytep dp = row + (png_size_t)(final_width - 1) * pixel_bytes;
 
-            int jstop = png_pass_inc[pass];
+            int jstop = (int)png_pass_inc[pass];
             png_uint_32 i;
 
             for (i = 0; i < row_info->width; i++)
@@ -3896,7 +3902,7 @@
 png_read_filter_row_paeth_multibyte_pixel(png_row_infop row_info, png_bytep row,
     png_const_bytep prev_row)
 {
-   int bpp = (row_info->pixel_depth + 7) >> 3;
+   unsigned int bpp = (row_info->pixel_depth + 7) >> 3;
    png_bytep rp_end = row + bpp;
 
    /* Process the first pixel in the row completely (this is the same as 'up'
@@ -3909,7 +3915,7 @@
    }
 
    /* Remainder */
-   rp_end += row_info->rowbytes - bpp;
+   rp_end = rp_end + (row_info->rowbytes - bpp);
 
    while (row < rp_end)
    {
@@ -4101,7 +4107,15 @@
          png_zstream_error(png_ptr, ret);
 
          if (output != NULL)
-            png_chunk_error(png_ptr, png_ptr->zstream.msg);
+         {
+            if(!strncmp(png_ptr->zstream.msg,"incorrect data check",20))
+            {
+               png_chunk_benign_error(png_ptr, "ADLER32 checksum mismatch");
+               continue;
+            }
+            else
+               png_chunk_error(png_ptr, png_ptr->zstream.msg);
+         }
 
          else /* checking */
          {
@@ -4254,7 +4268,7 @@
    /* Offset to next interlace block in the y direction */
    static PNG_CONST png_byte png_pass_yinc[7] = {8, 8, 8, 4, 4, 2, 2};
 
-   int max_pixel_depth;
+   unsigned int max_pixel_depth;
    png_size_t row_bytes;
 
    png_debug(1, "in png_read_start_row");
@@ -4283,7 +4297,7 @@
       png_ptr->iwidth = png_ptr->width;
    }
 
-   max_pixel_depth = png_ptr->pixel_depth;
+   max_pixel_depth = (unsigned int)png_ptr->pixel_depth;
 
    /* WARNING: * png_read_transform_info (pngrtran.c) performs a simpler set of
     * calculations to calculate the final pixel depth, then
@@ -4418,7 +4432,7 @@
 defined(PNG_USER_TRANSFORM_PTR_SUPPORTED)
    if ((png_ptr->transformations & PNG_USER_TRANSFORM) != 0)
    {
-      int user_pixel_depth = png_ptr->user_transform_depth *
+      unsigned int user_pixel_depth = png_ptr->user_transform_depth *
          png_ptr->user_transform_channels;
 
       if (user_pixel_depth > max_pixel_depth)
@@ -4440,7 +4454,7 @@
     * for safety's sake
     */
    row_bytes = PNG_ROWBYTES(max_pixel_depth, row_bytes) +
-       1 + ((max_pixel_depth + 7) >> 3);
+       1 + ((max_pixel_depth + 7) >> 3U);
 
 #ifdef PNG_MAX_MALLOC_64K
    if (row_bytes > (png_uint_32)65536L)
@@ -4509,7 +4523,7 @@
     * does not, so free the read buffer now regardless; the sequential reader
     * reallocates it on demand.
     */
-   if (png_ptr->read_buffer != 0)
+   if (png_ptr->read_buffer != NULL)
    {
       png_bytep buffer = png_ptr->read_buffer;
 
diff --git a/pngset.c b/pngset.c
index cccd9cd..28ff3a0 100644
--- a/pngset.c
+++ b/pngset.c
@@ -1,7 +1,7 @@
 
 /* pngset.c - storage of image information into info struct
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -283,17 +283,29 @@
 
    /* Check that the type matches the specification. */
    if (type < 0 || type > 3)
-      png_error(png_ptr, "Invalid pCAL equation type");
+   {
+      png_chunk_report(png_ptr, "Invalid pCAL equation type",
+            PNG_CHUNK_WRITE_ERROR);
+      return;
+   }
 
    if (nparams < 0 || nparams > 255)
-      png_error(png_ptr, "Invalid pCAL parameter count");
+   {
+      png_chunk_report(png_ptr, "Invalid pCAL parameter count",
+            PNG_CHUNK_WRITE_ERROR);
+      return;
+   }
 
    /* Validate params[nparams] */
    for (i=0; i<nparams; ++i)
    {
       if (params[i] == NULL ||
           !png_check_fp_string(params[i], strlen(params[i])))
-         png_error(png_ptr, "Invalid format for pCAL parameter");
+      {
+         png_chunk_report(png_ptr, "Invalid format for pCAL parameter",
+               PNG_CHUNK_WRITE_ERROR);
+         return;
+      }
    }
 
    info_ptr->pcal_purpose = png_voidcast(png_charp,
@@ -301,8 +313,8 @@
 
    if (info_ptr->pcal_purpose == NULL)
    {
-      png_warning(png_ptr, "Insufficient memory for pCAL purpose");
-
+      png_chunk_report(png_ptr, "Insufficient memory for pCAL purpose",
+            PNG_CHUNK_WRITE_ERROR);
       return;
    }
 
@@ -331,7 +343,7 @@
    memcpy(info_ptr->pcal_units, units, length);
 
    info_ptr->pcal_params = png_voidcast(png_charpp, png_malloc_warn(png_ptr,
-       (png_size_t)((nparams + 1) * (sizeof (png_charp)))));
+       (png_size_t)(((unsigned int)nparams + 1) * (sizeof (png_charp)))));
 
    if (info_ptr->pcal_params == NULL)
    {
@@ -340,7 +352,8 @@
       return;
    }
 
-   memset(info_ptr->pcal_params, 0, (nparams + 1) * (sizeof (png_charp)));
+   memset(info_ptr->pcal_params, 0, ((unsigned int)nparams + 1) *
+       (sizeof (png_charp)));
 
    for (i = 0; i < nparams; i++)
    {
@@ -563,7 +576,8 @@
        PNG_MAX_PALETTE_LENGTH * (sizeof (png_color))));
 
    if (num_palette > 0)
-      memcpy(png_ptr->palette, palette, num_palette * (sizeof (png_color)));
+      memcpy(png_ptr->palette, palette, (unsigned int)num_palette *
+          (sizeof (png_color)));
    info_ptr->palette = png_ptr->palette;
    info_ptr->num_palette = png_ptr->num_palette = (png_uint_16)num_palette;
 
@@ -1080,7 +1094,7 @@
        * checked it when doing the allocation.
        */
       memcpy(np->entries, entries->entries,
-          entries->nentries * sizeof (png_sPLT_entry));
+          (unsigned int)entries->nentries * sizeof (png_sPLT_entry));
 
       /* Note that 'continue' skips the advance of the out pointer and out
        * count, so an invalid entry is not added.
@@ -1249,7 +1263,7 @@
       {
          png_app_error(png_ptr, "invalid unknown chunk location");
          /* Fake out the pre 1.6.0 behavior: */
-         if ((location & PNG_HAVE_IDAT) != 0) /* undocumented! */
+         if (((unsigned int)location & PNG_HAVE_IDAT) != 0) /* undocumented! */
             location = PNG_AFTER_IDAT;
 
          else
@@ -1373,7 +1387,7 @@
          return;
       }
 
-      num_chunks = num_chunks_in;
+      num_chunks = (unsigned int)num_chunks_in;
    }
 
    old_num_chunks = png_ptr->num_chunk_list;
@@ -1563,7 +1577,7 @@
 png_set_invalid(png_const_structrp png_ptr, png_inforp info_ptr, int mask)
 {
    if (png_ptr != NULL && info_ptr != NULL)
-      info_ptr->valid &= ~mask;
+      info_ptr->valid &= (unsigned int)(~mask);
 }
 
 
diff --git a/pngstruct.h b/pngstruct.h
index 2b0eb49..55516ea 100644
--- a/pngstruct.h
+++ b/pngstruct.h
@@ -263,7 +263,7 @@
                               /* pixel depth used for the row buffers */
    png_byte transformed_pixel_depth;
                               /* pixel depth after read/write transforms */
-#if PNG_ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1240
    png_byte zstream_start;    /* at start of an input zlib stream */
 #endif /* Zlib >= 1.2.4 */
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
diff --git a/pngtest.c b/pngtest.c
index 9034d16..dd558dd 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -1,7 +1,7 @@
 
 /* pngtest.c - a simple test program to test libpng
  *
- * Last changed in libpng 1.6.25 [September 1, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -43,15 +43,6 @@
 
 #include "png.h"
 
-/* 1.6.1 added support for the configure test harness, which uses 77 to indicate
- * a skipped test, in earlier versions we need to succeed on a skipped test, so:
- */
-#if PNG_LIBPNG_VER >= 10601 && defined(HAVE_CONFIG_H)
-#  define SKIP 77
-#else
-#  define SKIP 0
-#endif
-
 /* Known chunks that exist in pngtest.png must be supported or pngtest will fail
  * simply as a result of re-ordering them.  This may be fixed in 1.7
  *
@@ -514,10 +505,10 @@
 typedef memory_information *memory_infop;
 
 static memory_infop pinformation = NULL;
-static png_alloc_size_t current_allocation = 0;
-static png_alloc_size_t maximum_allocation = 0;
-static png_alloc_size_t total_allocation = 0;
-static png_alloc_size_t num_allocations = 0;
+static int current_allocation = 0;
+static int maximum_allocation = 0;
+static int total_allocation = 0;
+static int num_allocations = 0;
 
 png_voidp PNGCBAPI png_debug_malloc PNGARG((png_structp png_ptr,
     png_alloc_size_t size));
@@ -604,10 +595,9 @@
          if (pinfo->pointer == ptr)
          {
             *ppinfo = pinfo->next;
-            if (current_allocation < pinfo->size)
+            current_allocation -= pinfo->size;
+            if (current_allocation < 0)
                fprintf(STDERR, "Duplicate free of memory\n");
-            else
-               current_allocation -= pinfo->size;
             /* We must free the list element too, but first kill
                the memory that is to be freed. */
             memset(ptr, 0x55, pinfo->size);
@@ -939,12 +929,6 @@
        read_user_chunk_callback);
 #endif
 
-#ifdef PNG_SET_USER_LIMITS_SUPPORTED
-#  ifdef CHUNK_LIMIT /* from the build, for testing */
-      png_set_chunk_malloc_max(read_ptr, CHUNK_LIMIT);
-#  endif /* CHUNK_LIMIT */
-#endif
-
 #ifdef PNG_SETJMP_SUPPORTED
    pngtest_debug("Setting jmpbuf for read struct");
    if (setjmp(png_jmpbuf(read_ptr)))
@@ -980,15 +964,16 @@
 #endif
 #endif
 
+#ifdef PNG_BENIGN_ERRORS_SUPPORTED
    if (strict != 0)
    {
       /* Treat png_benign_error() as errors on read */
       png_set_benign_errors(read_ptr, 0);
 
-#ifdef PNG_WRITE_SUPPORTED
+# ifdef PNG_WRITE_SUPPORTED
       /* Treat them as errors on write */
       png_set_benign_errors(write_ptr, 0);
-#endif
+# endif
 
       /* if strict is not set, then app warnings and errors are treated as
        * warnings in release builds, but not in unstable builds; this can be
@@ -1001,10 +986,15 @@
       /* Allow application (pngtest) errors and warnings to pass */
       png_set_benign_errors(read_ptr, 1);
 
-#ifdef PNG_WRITE_SUPPORTED
+      /* Turn off CRC and ADLER32 checking while reading */
+      png_set_crc_action(read_ptr, PNG_CRC_QUIET_USE, PNG_CRC_QUIET_USE);
+
+# ifdef PNG_WRITE_SUPPORTED
       png_set_benign_errors(write_ptr, 1);
-#endif
+# endif
+
    }
+#endif /* BENIGN_ERRORS */
 
    pngtest_debug("Initializing input and output streams");
 #ifdef PNG_STDIO_SUPPORTED
@@ -1402,6 +1392,11 @@
    png_write_info(write_ptr, write_info_ptr);
 
    write_chunks(write_ptr, before_IDAT); /* after PLTE */
+
+#ifdef PNG_COMPRESSION_COMPAT
+   /* Test the 'compatibility' setting here, if it is available. */
+   png_set_compression(write_ptr, PNG_COMPRESSION_COMPAT);
+#endif
 #endif
 
 #ifdef SINGLE_ROWBUF_ALLOC
@@ -1883,7 +1878,7 @@
    {
       int i;
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
-      png_alloc_size_t allocation_now = current_allocation;
+      int allocation_now = current_allocation;
 #endif
       for (i=2; i<argc; ++i)
       {
@@ -1916,15 +1911,15 @@
          }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
          if (allocation_now != current_allocation)
-            fprintf(STDERR, "MEMORY ERROR: %lu bytes lost\n",
-                (unsigned long)(current_allocation - allocation_now));
+            fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
+                current_allocation - allocation_now);
 
          if (current_allocation != 0)
          {
             memory_infop pinfo = pinformation;
 
-            fprintf(STDERR, "MEMORY ERROR: %lu bytes still allocated\n",
-                (unsigned long)current_allocation);
+            fprintf(STDERR, "MEMORY ERROR: %d bytes still allocated\n",
+                current_allocation);
 
             while (pinfo != NULL)
             {
@@ -1937,14 +1932,14 @@
 #endif
       }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
-         fprintf(STDERR, " Current memory allocation: %20lu bytes\n",
-             (unsigned long)current_allocation);
-         fprintf(STDERR, " Maximum memory allocation: %20lu bytes\n",
-             (unsigned long) maximum_allocation);
-         fprintf(STDERR, " Total   memory allocation: %20lu bytes\n",
-             (unsigned long)total_allocation);
-         fprintf(STDERR, "     Number of allocations: %20lu\n",
-             (unsigned long)num_allocations);
+         fprintf(STDERR, " Current memory allocation: %10d bytes\n",
+             current_allocation);
+         fprintf(STDERR, " Maximum memory allocation: %10d bytes\n",
+             maximum_allocation);
+         fprintf(STDERR, " Total   memory allocation: %10d bytes\n",
+             total_allocation);
+         fprintf(STDERR, "     Number of allocations: %10d\n",
+             num_allocations);
 #endif
    }
 
@@ -1955,7 +1950,7 @@
       {
          int kerror;
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
-         png_alloc_size_t allocation_now = current_allocation;
+         int allocation_now = current_allocation;
 #endif
          if (i == 1)
             status_dots_requested = 1;
@@ -2005,15 +2000,15 @@
          }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
          if (allocation_now != current_allocation)
-             fprintf(STDERR, "MEMORY ERROR: %lu bytes lost\n",
-                 (unsigned long)(current_allocation - allocation_now));
+             fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
+                 current_allocation - allocation_now);
 
          if (current_allocation != 0)
          {
              memory_infop pinfo = pinformation;
 
-             fprintf(STDERR, "MEMORY ERROR: %lu bytes still allocated\n",
-                 (unsigned long)current_allocation);
+             fprintf(STDERR, "MEMORY ERROR: %d bytes still allocated\n",
+                 current_allocation);
 
              while (pinfo != NULL)
              {
@@ -2025,14 +2020,14 @@
 #endif
        }
 #if defined(PNG_USER_MEM_SUPPORTED) && PNG_DEBUG
-       fprintf(STDERR, " Current memory allocation: %20lu bytes\n",
-           (unsigned long)current_allocation);
-       fprintf(STDERR, " Maximum memory allocation: %20lu bytes\n",
-           (unsigned long)maximum_allocation);
-       fprintf(STDERR, " Total   memory allocation: %20lu bytes\n",
-           (unsigned long)total_allocation);
-       fprintf(STDERR, "     Number of allocations: %20lu\n",
-           (unsigned long)num_allocations);
+       fprintf(STDERR, " Current memory allocation: %10d bytes\n",
+           current_allocation);
+       fprintf(STDERR, " Maximum memory allocation: %10d bytes\n",
+           maximum_allocation);
+       fprintf(STDERR, " Total   memory allocation: %10d bytes\n",
+           total_allocation);
+       fprintf(STDERR, "     Number of allocations: %10d\n",
+           num_allocations);
 #endif
    }
 
@@ -2083,9 +2078,9 @@
    fprintf(STDERR,
        " test ignored because libpng was not built with read support\n");
    /* And skip this test */
-   return SKIP;
+   return PNG_LIBPNG_VER < 10600 ? 0 : 77;
 }
 #endif
 
 /* Generate a compiler error if there is an old png.h in the search path. */
-typedef png_libpng_version_1_6_25 Your_png_h_is_not_version_1_6_25;
+typedef png_libpng_version_1_6_26 Your_png_h_is_not_version_1_6_26;
diff --git a/pngtrans.c b/pngtrans.c
index e5cbd79..da7413f 100644
--- a/pngtrans.c
+++ b/pngtrans.c
@@ -1,7 +1,7 @@
 
 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -595,7 +595,7 @@
       return; /* The filler channel has gone already */
 
    /* Fix the rowbytes value. */
-   row_info->rowbytes = dp-row;
+   row_info->rowbytes = (unsigned int)(dp-row);
 }
 #endif
 
@@ -693,7 +693,7 @@
        * and this calculation is used because it avoids warnings that other
        * forms produced on either GCC or MSVC.
        */
-      int padding = (-row_info->pixel_depth * row_info->width) & 7;
+      int padding = PNG_PADBITS(row_info->pixel_depth, row_info->width);
       png_bytep rp = png_ptr->row_buf + row_info->rowbytes;
 
       switch (row_info->bit_depth)
diff --git a/pngwrite.c b/pngwrite.c
index aaa2b01..07088ee 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -1,7 +1,7 @@
 
 /* pngwrite.c - general routines to write a PNG file
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -666,9 +666,9 @@
 
          for (i = 0, rp = row; i < row_width; i++, rp += bytes_per_pixel)
          {
-            png_uint_32 s0   = (*(rp    ) << 8) | *(rp + 1);
-            png_uint_32 s1   = (*(rp + 2) << 8) | *(rp + 3);
-            png_uint_32 s2   = (*(rp + 4) << 8) | *(rp + 5);
+            png_uint_32 s0   = (png_uint_32)(*(rp    ) << 8) | *(rp + 1);
+            png_uint_32 s1   = (png_uint_32)(*(rp + 2) << 8) | *(rp + 3);
+            png_uint_32 s2   = (png_uint_32)(*(rp + 4) << 8) | *(rp + 5);
             png_uint_32 red  = (png_uint_32)((s0 - s1) & 0xffffL);
             png_uint_32 blue = (png_uint_32)((s2 - s1) & 0xffffL);
             *(rp    ) = (png_byte)(red >> 8);
@@ -901,7 +901,7 @@
    if (png_ptr == NULL)
       return;
 
-   png_ptr->flush_dist = (nrows < 0 ? 0 : nrows);
+   png_ptr->flush_dist = (nrows < 0 ? 0 : (png_uint_32)nrows);
 }
 
 /* Flush the current output buffers now */
@@ -1525,7 +1525,8 @@
        display->first_row);
    png_uint_16p output_row = png_voidcast(png_uint_16p, display->local_row);
    png_uint_16p row_end;
-   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
+   const unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
+       3 : 1;
    int aindex = 0;
    png_uint_32 y = image->height;
 
@@ -1539,9 +1540,9 @@
          ++output_row;
       }
          else
-            aindex = channels;
+            aindex = (int)channels;
 #     else
-         aindex = channels;
+         aindex = (int)channels;
 #     endif
    }
 
@@ -1554,7 +1555,7 @@
     */
    row_end = output_row + image->width * (channels+1);
 
-   while (y-- > 0)
+   for (; y > 0; --y)
    {
       png_const_uint_16p in_ptr = input_row;
       png_uint_16p out_ptr = output_row;
@@ -1575,7 +1576,7 @@
          if (alpha > 0 && alpha < 65535)
             reciprocal = ((0xffff<<15)+(alpha>>1))/alpha;
 
-         c = channels;
+         c = (int)channels;
          do /* always at least one channel */
          {
             png_uint_16 component = *in_ptr++;
@@ -1610,7 +1611,7 @@
       }
 
       png_write_row(png_ptr, png_voidcast(png_const_bytep, display->local_row));
-      input_row += display->row_bytes/(sizeof (png_uint_16));
+      input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
    }
 
    return 1;
@@ -1683,7 +1684,8 @@
        display->first_row);
    png_bytep output_row = png_voidcast(png_bytep, display->local_row);
    png_uint_32 y = image->height;
-   const int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ? 3 : 1;
+   const unsigned int channels = (image->format & PNG_FORMAT_FLAG_COLOR) != 0 ?
+       3 : 1;
 
    if ((image->format & PNG_FORMAT_FLAG_ALPHA) != 0)
    {
@@ -1700,12 +1702,12 @@
 
       else
 #   endif
-      aindex = channels;
+      aindex = (int)channels;
 
       /* Use row_end in place of a loop counter: */
       row_end = output_row + image->width * (channels+1);
 
-      while (y-- > 0)
+      for (; y > 0; --y)
       {
          png_const_uint_16p in_ptr = input_row;
          png_bytep out_ptr = output_row;
@@ -1723,7 +1725,7 @@
             if (alphabyte > 0 && alphabyte < 255)
                reciprocal = UNP_RECIPROCAL(alpha);
 
-            c = channels;
+            c = (int)channels;
             do /* always at least one channel */
                *out_ptr++ = png_unpremultiply(*in_ptr++, alpha, reciprocal);
             while (--c > 0);
@@ -1735,7 +1737,7 @@
 
          png_write_row(png_ptr, png_voidcast(png_const_bytep,
              display->local_row));
-         input_row += display->row_bytes/(sizeof (png_uint_16));
+         input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
       } /* while y */
    }
 
@@ -1746,7 +1748,7 @@
        */
       png_bytep row_end = output_row + image->width * channels;
 
-      while (y-- > 0)
+      for (; y > 0; --y)
       {
          png_const_uint_16p in_ptr = input_row;
          png_bytep out_ptr = output_row;
@@ -1760,7 +1762,7 @@
          }
 
          png_write_row(png_ptr, output_row);
-         input_row += display->row_bytes/(sizeof (png_uint_16));
+         input_row += (png_uint_16)display->row_bytes/(sizeof (png_uint_16));
       }
    }
 
@@ -1777,7 +1779,7 @@
 
    /* NOTE: the caller must check for cmap != NULL and entries != 0 */
    const png_uint_32 format = image->format;
-   const int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
+   const unsigned int channels = PNG_IMAGE_SAMPLE_CHANNELS(format);
 
 #   if defined(PNG_FORMAT_BGR_SUPPORTED) &&\
       defined(PNG_SIMPLIFIED_WRITE_AFIRST_SUPPORTED)
@@ -1809,7 +1811,7 @@
       {
          png_const_uint_16p entry = png_voidcast(png_const_uint_16p, cmap);
 
-         entry += i * channels;
+         entry += (unsigned int)i * channels;
 
          if ((channels & 1) != 0) /* no alpha */
          {
@@ -1865,7 +1867,7 @@
       {
          png_const_bytep entry = png_voidcast(png_const_bytep, cmap);
 
-         entry += i * channels;
+         entry += (unsigned int)i * channels;
 
          switch (channels)
          {
@@ -1910,7 +1912,7 @@
       png_set_tRNS(image->opaque->png_ptr, image->opaque->info_ptr, tRNS,
           num_trans, NULL);
 
-   image->colormap_entries = entries;
+   image->colormap_entries = (png_uint_32)entries;
 }
 
 static int
@@ -1940,7 +1942,7 @@
    {
       const unsigned int channels = PNG_IMAGE_PIXEL_CHANNELS(image->format);
 
-      if (image->width <= 0x7FFFFFFFU/channels) /* no overflow */
+      if (image->width <= 0x7fffffffU/channels) /* no overflow */
       {
          png_uint_32 check;
          const png_uint_32 png_row_stride = image->width * channels;
@@ -1949,10 +1951,10 @@
             display->row_stride = (png_int_32)/*SAFE*/png_row_stride;
 
          if (display->row_stride < 0)
-            check = -display->row_stride;
+            check = (png_uint_32)(-display->row_stride);
 
          else
-            check = display->row_stride;
+            check = (png_uint_32)display->row_stride;
 
          if (check >= png_row_stride)
          {
@@ -1960,7 +1962,7 @@
              * limits the whole image size to 32 bits for API compatibility with
              * the current, 32-bit, PNG_IMAGE_BUFFER_SIZE macro.
              */
-            if (image->height > 0xFFFFFFFF/png_row_stride)
+            if (image->height > 0xffffffffU/png_row_stride)
                png_error(image->opaque->png_ptr, "memory image too large");
          }
 
@@ -2136,7 +2138,7 @@
       ptrdiff_t row_bytes = display->row_bytes;
       png_uint_32 y = image->height;
 
-      while (y-- > 0)
+      for (; y > 0; --y)
       {
          png_write_row(png_ptr, row);
          row += row_bytes;
diff --git a/pngwtran.c b/pngwtran.c
index 423fb2d..377b43e 100644
--- a/pngwtran.c
+++ b/pngwtran.c
@@ -1,7 +1,7 @@
 
 /* pngwtran.c - transforms the data in a row for PNG writers
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -177,7 +177,7 @@
    if (row_info->color_type != PNG_COLOR_TYPE_PALETTE)
    {
       int shift_start[4], shift_dec[4];
-      int channels = 0;
+      unsigned int channels = 0;
 
       if ((row_info->color_type & PNG_COLOR_MASK_COLOR) != 0)
       {
diff --git a/pngwutil.c b/pngwutil.c
index 3f1ed0c..d1a82d4 100644
--- a/pngwutil.c
+++ b/pngwutil.c
@@ -1,7 +1,7 @@
 
 /* pngwutil.c - utilities to write a PNG file
  *
- * Last changed in libpng 1.6.24 [August 4, 2016]
+ * Last changed in libpng 1.6.26 [October 20, 2016]
  * Copyright (c) 1998-2002,2004,2006-2016 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -408,7 +408,7 @@
       png_ptr->zstream.avail_out = 0;
 
       /* Now initialize if required, setting the new parameters, otherwise just
-       * to a simple reset to the previous parameters.
+       * do a simple reset to the previous parameters.
        */
       if ((png_ptr->flags & PNG_FLAG_ZSTREAM_INITIALIZED) != 0)
          ret = deflateReset(&png_ptr->zstream);
@@ -1176,7 +1176,7 @@
    png_byte new_name[80];
    png_byte entrybuf[10];
    png_size_t entry_size = (spalette->depth == 8 ? 6 : 10);
-   png_size_t palette_size = entry_size * spalette->nentries;
+   png_size_t palette_size = entry_size * (png_size_t)spalette->nentries;
    png_sPLT_entryp ep;
 #ifndef PNG_POINTER_INDEXING_SUPPORTED
    int i;
@@ -1743,7 +1743,7 @@
    total_len = purpose_len + units_len + 10;
 
    params_len = (png_size_tp)png_malloc(png_ptr,
-       (png_alloc_size_t)(nparams * (sizeof (png_size_t))));
+       (png_alloc_size_t)((png_alloc_size_t)nparams * (sizeof (png_size_t))));
 
    /* Find the length of each parameter, making sure we don't count the
     * null terminator for the last parameter.
@@ -2255,7 +2255,7 @@
    png_bytep rp, dp, lp;
    png_size_t i;
    png_size_t sum = 0;
-   int v;
+   unsigned int v;
 
    png_ptr->try_row[0] = PNG_FILTER_VALUE_SUB;
 
@@ -2264,7 +2264,7 @@
    {
       v = *dp = *rp;
 #ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
+      sum += 128 - abs((int)v - 128);
 #else
       sum += (v < 128) ? v : 256 - v;
 #endif
@@ -2275,7 +2275,7 @@
    {
       v = *dp = (png_byte)(((int)*rp - (int)*lp) & 0xff);
 #ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
+      sum += 128 - abs((int)v - 128);
 #else
       sum += (v < 128) ? v : 256 - v;
 #endif
@@ -2316,7 +2316,7 @@
    png_bytep rp, dp, pp;
    png_size_t i;
    png_size_t sum = 0;
-   int v;
+   unsigned int v;
 
    png_ptr->try_row[0] = PNG_FILTER_VALUE_UP;
 
@@ -2326,7 +2326,7 @@
    {
       v = *dp = (png_byte)(((int)*rp - (int)*pp) & 0xff);
 #ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
+      sum += 128 - abs((int)v - 128);
 #else
       sum += (v < 128) ? v : 256 - v;
 #endif
@@ -2360,7 +2360,7 @@
    png_bytep rp, dp, pp, lp;
    png_uint_32 i;
    png_size_t sum = 0;
-   int v;
+   unsigned int v;
 
    png_ptr->try_row[0] = PNG_FILTER_VALUE_AVG;
 
@@ -2370,7 +2370,7 @@
       v = *dp++ = (png_byte)(((int)*rp++ - ((int)*pp++ / 2)) & 0xff);
 
 #ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
+      sum += 128 - abs((int)v - 128);
 #else
       sum += (v < 128) ? v : 256 - v;
 #endif
@@ -2382,7 +2382,7 @@
           & 0xff);
 
 #ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
+      sum += 128 - abs((int)v - 128);
 #else
       sum += (v < 128) ? v : 256 - v;
 #endif
@@ -2422,7 +2422,7 @@
    png_bytep rp, dp, pp, cp, lp;
    png_size_t i;
    png_size_t sum = 0;
-   int v;
+   unsigned int v;
 
    png_ptr->try_row[0] = PNG_FILTER_VALUE_PAETH;
 
@@ -2432,7 +2432,7 @@
       v = *dp++ = (png_byte)(((int)*rp++ - (int)*pp++) & 0xff);
 
 #ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
+      sum += 128 - abs((int)v - 128);
 #else
       sum += (v < 128) ? v : 256 - v;
 #endif
@@ -2465,7 +2465,7 @@
       v = *dp++ = (png_byte)(((int)*rp++ - p) & 0xff);
 
 #ifdef PNG_USE_ABS
-      sum += 128 - abs(v - 128);
+      sum += 128 - abs((int)v - 128);
 #else
       sum += (v < 128) ? v : 256 - v;
 #endif
@@ -2588,14 +2588,14 @@
       png_bytep rp;
       png_size_t sum = 0;
       png_size_t i;
-      int v;
+      unsigned int v;
 
       {
          for (i = 0, rp = row_buf + 1; i < row_bytes; i++, rp++)
          {
             v = *rp;
 #ifdef PNG_USE_ABS
-            sum += 128 - abs(v - 128);
+            sum += 128 - abs((int)v - 128);
 #else
             sum += (v < 128) ? v : 256 - v;
 #endif
diff --git a/projects/vstudio/README.txt b/projects/vstudio/README.txt
index 0457c2d..643b763 100644
--- a/projects/vstudio/README.txt
+++ b/projects/vstudio/README.txt
@@ -1,7 +1,7 @@
 
 VisualStudio instructions
 
-libpng version 1.6.25 - September 1, 2016
+libpng version 1.6.26 - October 20, 2016
 
 Copyright (c) 2010,2013,2015 Glenn Randers-Pehrson
 
diff --git a/projects/vstudio/zlib.props b/projects/vstudio/zlib.props
index 8adbd1e..b7ab242 100644
--- a/projects/vstudio/zlib.props
+++ b/projects/vstudio/zlib.props
@@ -2,7 +2,7 @@
 <!--
  * zlib.props - location of zlib source
  *
- * libpng version 1.6.25 - September 1, 2016
+ * libpng version 1.6.26 - October 20, 2016
  *
  * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  *
diff --git a/scripts/README.txt b/scripts/README.txt
index 242da14..71aeebe 100644
--- a/scripts/README.txt
+++ b/scripts/README.txt
@@ -1,9 +1,9 @@
 
-Makefiles for  libpng version 1.6.25 - September 1, 2016
+Makefiles for  libpng version 1.6.26 - October 20, 2016
 
 pnglibconf.h.prebuilt       =>  Stores configuration settings
  makefile.linux    =>  Linux/ELF makefile
-                       (gcc, creates libpng16.so.16.1.6.25)
+                       (gcc, creates libpng16.so.16.1.6.26)
  makefile.gcc      =>  Generic makefile (gcc, creates static libpng.a)
  makefile.knr      =>  Archaic UNIX Makefile that converts files with
                        ansi2knr (Requires ansi2knr.c from
@@ -33,12 +33,12 @@
  makefile.os2      =>  OS/2 Makefile (gcc and emx, requires libpng.def)
  makefile.sco      =>  For SCO OSr5  ELF and Unixware 7 with Native cc
  makefile.sggcc    =>  Silicon Graphics (gcc,
-                       creates libpng16.so.16.1.6.25)
+                       creates libpng16.so.16.1.6.26)
  makefile.sgi      =>  Silicon Graphics IRIX makefile (cc, creates static lib)
  makefile.solaris  =>  Solaris 2.X makefile (gcc,
-                       creates libpng16.so.16.1.6.25)
+                       creates libpng16.so.16.1.6.26)
  makefile.so9      =>  Solaris 9 makefile (gcc,
-                       creates libpng16.so.16.1.6.25)
+                       creates libpng16.so.16.1.6.26)
  makefile.std      =>  Generic UNIX makefile (cc, creates static libpng.a)
  makefile.sunos    =>  Sun makefile
  makefile.32sunu   =>  Sun Ultra 32-bit makefile
diff --git a/scripts/def.c b/scripts/def.c
index 9aaa56e..7f2be6a 100644
--- a/scripts/def.c
+++ b/scripts/def.c
@@ -21,7 +21,7 @@
 PNG_DFN "OS2 CODE PRELOAD MOVEABLE DISCARDABLE"
 PNG_DFN ""
 PNG_DFN "EXPORTS"
-PNG_DFN ";Version 1.6.25"
+PNG_DFN ";Version 1.6.26"
 
 #define PNG_EXPORTA(ordinal, type, name, args, attributes)\
         PNG_DFN "@" SYMBOL_PREFIX "@@" name "@"
diff --git a/scripts/libpng-config-head.in b/scripts/libpng-config-head.in
index d889518..b78f908 100644
--- a/scripts/libpng-config-head.in
+++ b/scripts/libpng-config-head.in
@@ -11,7 +11,7 @@
 
 # Modeled after libxml-config.
 
-version=1.6.25
+version=1.6.26
 prefix=""
 libdir=""
 libs=""
diff --git a/scripts/libpng.pc.in b/scripts/libpng.pc.in
index 8263f8c..7a2cb2b 100644
--- a/scripts/libpng.pc.in
+++ b/scripts/libpng.pc.in
@@ -5,6 +5,6 @@
 
 Name: libpng
 Description: Loads and saves PNG files
-Version: 1.6.25
+Version: 1.6.26
 Libs: -L${libdir} -lpng16
 Cflags: -I${includedir}
diff --git a/scripts/makefile.cegcc b/scripts/makefile.cegcc
index d723658..93c1236 100644
--- a/scripts/makefile.cegcc
+++ b/scripts/makefile.cegcc
@@ -23,7 +23,7 @@
 
 VERMAJ = 1
 VERMIN = 6
-VERMIC = 25
+VERMIC = 26
 VER = $(VERMAJ).$(VERMIN).$(VERMIC)
 NAME = libpng
 PACKAGE = $(NAME)-$(VER)
diff --git a/scripts/makefile.linux b/scripts/makefile.linux
index c2bfac6..e7347f6 100644
--- a/scripts/makefile.linux
+++ b/scripts/makefile.linux
@@ -10,7 +10,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 25
+RELEASE = 26
 
 # Shared library names:
 LIBSO=$(LIBNAME).so
diff --git a/scripts/makefile.msys b/scripts/makefile.msys
index b0c0e3c..09429ee 100644
--- a/scripts/makefile.msys
+++ b/scripts/makefile.msys
@@ -18,7 +18,7 @@
 # Library name:
 LIBNAME = libpng16
 PNGMAJ = 16
-RELEASE = 25
+RELEASE = 26
 
 # Shared library names:
 LIBSO=$(LIBNAME).dll
diff --git a/scripts/makefile.ne12bsd b/scripts/makefile.ne12bsd
index 21ffe56..3d36688 100644
--- a/scripts/makefile.ne12bsd
+++ b/scripts/makefile.ne12bsd
@@ -17,7 +17,7 @@
 
 LIB=	png16
 SHLIB_MAJOR=	0
-SHLIB_MINOR=	1.6.25
+SHLIB_MINOR=	1.6.26
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
diff --git a/scripts/makefile.netbsd b/scripts/makefile.netbsd
index 0046f69..8fb2c76 100644
--- a/scripts/makefile.netbsd
+++ b/scripts/makefile.netbsd
@@ -17,7 +17,7 @@
 
 LIB=	png
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.25
+SHLIB_MINOR=	1.6.26
 SRCS=	png.c pngset.c pngget.c pngrutil.c pngtrans.c pngwutil.c \
 	pngread.c pngrio.c pngwio.c pngwrite.c pngrtran.c \
 	pngwtran.c pngmem.c pngerror.c pngpread.c
diff --git a/scripts/makefile.openbsd b/scripts/makefile.openbsd
index 756759f..35b1424 100644
--- a/scripts/makefile.openbsd
+++ b/scripts/makefile.openbsd
@@ -11,7 +11,7 @@
 MANDIR= ${PREFIX}/man/cat
 
 SHLIB_MAJOR=	16
-SHLIB_MINOR=	1.6.25
+SHLIB_MINOR=	1.6.26
 
 LIB=	png
 SRCS=	png.c pngerror.c pngget.c pngmem.c pngpread.c \
diff --git a/scripts/makefile.sco b/scripts/makefile.sco
index b9c7c40..67d84aa 100644
--- a/scripts/makefile.sco
+++ b/scripts/makefile.sco
@@ -1,5 +1,5 @@
 # makefile for SCO OSr5  ELF and Unixware 7 with Native cc
-# Contributed by Mike Hopkirk (hops@sco.com) modified from Makefile.lnx
+# Contributed by Mike Hopkirk (hops at sco.com) modified from Makefile.lnx
 #   force ELF build dynamic linking, SONAME setting in lib and RPATH in app
 # Copyright (C) 2002, 2006, 2010-2014 Glenn Randers-Pehrson
 # Copyright (C) 1998 Greg Roelofs
diff --git a/scripts/pnglibconf.h.prebuilt b/scripts/pnglibconf.h.prebuilt
index d7d21b2..ba7805f 100644
--- a/scripts/pnglibconf.h.prebuilt
+++ b/scripts/pnglibconf.h.prebuilt
@@ -1,8 +1,8 @@
-/* libpng 1.6.25 STANDARD API DEFINITION */
+/* libpng 1.6.26 STANDARD API DEFINITION */
 
 /* pnglibconf.h - library build configuration */
 
-/* Libpng version 1.6.25 - September 1, 2016 */
+/* Libpng version 1.6.26 - October 20, 2016 */
 
 /* Copyright (c) 1998-2015 Glenn Randers-Pehrson */
 
diff --git a/scripts/symbols.def b/scripts/symbols.def
index cdf7896..612d211 100644
--- a/scripts/symbols.def
+++ b/scripts/symbols.def
@@ -1,4 +1,4 @@
-;Version 1.6.25
+;Version 1.6.26
 ;--------------------------------------------------------------
 ; LIBPNG symbol list as a Win32 DEF file
 ; Contains all the symbols that can be exported from libpng
diff --git a/tests/badadler.png b/tests/badadler.png
new file mode 100644
index 0000000..2bcbcc9
--- /dev/null
+++ b/tests/badadler.png
Binary files differ
diff --git a/tests/badcrc.png b/tests/badcrc.png
new file mode 100644
index 0000000..45d0268
--- /dev/null
+++ b/tests/badcrc.png
Binary files differ
diff --git a/tests/pngtest b/tests/pngtest
index 813973b..d33f936 100755
--- a/tests/pngtest
+++ b/tests/pngtest
@@ -1,2 +1,4 @@
 #!/bin/sh
+./pngtest --relaxed ${srcdir}/tests/badcrc.png
+./pngtest --relaxed ${srcdir}/tests/badadler.png
 exec ./pngtest --strict ${srcdir}/pngtest.png