diff --git a/ChangeLog b/ChangeLog
index 5d229ed25..7184387f7 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2013-02-21 Riccardo Mottola <rm@gnu.org>
+
+	* Source/NSBitmapImageRep+PNG.m
+	Define png_sizeof() to allow compilation on 1.6.
+
 2013-02-19  Fred Kiefer <FredKiefer@gmx.de>
 
 	* Tools/make_services.m (main, CheckDirectory)
diff --git a/Source/NSBitmapImageRep+PNG.m b/Source/NSBitmapImageRep+PNG.m
index 0011da037..0c0a00d94 100644
--- a/Source/NSBitmapImageRep+PNG.m
+++ b/Source/NSBitmapImageRep+PNG.m
@@ -3,7 +3,7 @@
 
    Methods for loading .png images.
 
-   Copyright (C) 2003-2011 Free Software Foundation, Inc.
+   Copyright (C) 2003-2013 Free Software Foundation, Inc.
    
    Written by: Alexander Malmberg <alexander@malmberg.org>
    Date: 2003-12-07
@@ -48,6 +48,10 @@
 
 #endif /* HAVE_LIBPNG */
 
+#if !defined png_sizeof
+#define png_sizeof(x) sizeof(x)
+#endif
+
 /* we import all the standard headers to allow compilation without PNG */
 #import <Foundation/NSData.h>
 #import <Foundation/NSDictionary.h>