diff --git a/libpng-manual.txt b/libpng-manual.txt
index 5dad92fbf..6d8e8eb88 100644
--- a/libpng-manual.txt
+++ b/libpng-manual.txt
@@ -1792,7 +1792,7 @@ the information.  If, instead, you want to convert the image to an opaque
 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 conversion of grayscale to indexed images (which can be
+major omissions 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.)
 
diff --git a/libpng.3 b/libpng.3
index f37423540..4bd961a1b 100644
--- a/libpng.3
+++ b/libpng.3
@@ -2311,7 +2311,7 @@ the information.  If, instead, you want to convert the image to an opaque
 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 conversion of grayscale to indexed images (which can be
+major omissions 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.)