diff --git a/libpng-manual.txt b/libpng-manual.txt
index 490c23a..7ec2fa2 100644
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1451,8 +1451,8 @@
 version with no alpha channel use png_set_background; see below.
 
 As of libpng version 1.5.2, almost all useful expansions are supported, the
-major ommissions are convertion of grayscale to indexed images (which can be
-done trivially in the application) and convertion of indexed to grayscale (which
+major ommissions are conversion of grayscale to indexed images (which can be
+done trivially in the application) and conversion of indexed to grayscale (which
 can be done by a trivial manipulation of the palette.)
 
 In the following table, the 01 means grayscale with depth<8, 31 means
diff --git a/libpng.3 b/libpng.3
index 6611648..db5db7f 100644
--- a/libpng.3
+++ b/libpng.3
@@ -2402,8 +2402,8 @@
 version with no alpha channel use png_set_background; see below.
 
 As of libpng version 1.5.2, almost all useful expansions are supported, the
-major ommissions are convertion of grayscale to indexed images (which can be
-done trivially in the application) and convertion of indexed to grayscale (which
+major ommissions are conversion of grayscale to indexed images (which can be
+done trivially in the application) and conversion of indexed to grayscale (which
 can be done by a trivial manipulation of the palette.)
 
 In the following table, the 01 means grayscale with depth<8, 31 means