diff --git a/ANNOUNCE b/ANNOUNCE
index 3ae4dff..c3edcfb 100644
--- a/ANNOUNCE
+++ b/ANNOUNCE
@@ -1,4 +1,4 @@
-Libpng 1.6.26beta06 - October 6, 2016
+Libpng 1.6.26beta06 - October 7, 2016
 
 This is not intended to be a public release.  It will be replaced
 within a few weeks by a public version or by another test version.
@@ -65,7 +65,9 @@
   Changed integer constant 4294967294 to unsigned 4294967294U in pngconf.h
     to avoid a signed/unsigned compare in the preprocessor.
 
-Version 1.6.26beta05 [October 6, 2016]
+Version 1.6.26beta05 [October 7, 2016]
+  Use zlib-1.2.8.1 inflateValidate() instead of inflateReset2() to
+    avoid ADLER32 evaluation.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/CHANGES b/CHANGES
index f7a8f87..ac90163 100644
--- a/CHANGES
+++ b/CHANGES
@@ -5743,7 +5743,9 @@
   Changed integer constant 4294967294 to unsigned 4294967294U in pngconf.h
     to avoid a signed/unsigned compare in the preprocessor.
 
-Version 1.6.26beta05 [October 6, 2016]
+Version 1.6.26beta05 [October 7, 2016]
+  Use zlib-1.2.8.1 inflateValidate() instead of inflateReset2() to
+    avoid ADLER32 evaluation.
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net
 (subscription required; visit
diff --git a/pngrutil.c b/pngrutil.c
index ab72bcc..25f44b1 100644
--- a/pngrutil.c
+++ b/pngrutil.c
@@ -418,10 +418,10 @@
             png_ptr->flags |= PNG_FLAG_ZSTREAM_INITIALIZED;
       }
 
-#if ZLIB_VERNUM >= 0x1240
+#if ZLIB_VERNUM >= 0x1281
       /* Turn off validation of the ADLER32 checksum */
       if ((png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) != 0)
-         ret = inflateReset2(&png_ptr->zstream, -window_bits);
+         ret = inflateValidate(&png_ptr->zstream, 0);
 #endif
 
       if (ret == Z_OK)