diff -Nur gd-2.0.36RC1.orig/gd_png.c gd-2.0.36RC1/gd_png.c
--- gd-2.0.36RC1.orig/gd_png.c	2007-11-27 10:30:34.000000000 +0200
+++ gd-2.0.36RC1/gd_png.c	2010-01-17 17:14:11.000000000 +0200
@@ -151,7 +151,7 @@
 	return NULL;
   }
 
-	if (!png_check_sig (sig, 8)) { /* bad signature */
+	if (png_sig_cmp (sig, 0, 8)) { /* bad signature */
     	return NULL;		/* bad signature */
 	}