$OpenBSD$
--- src/engine/IMG_savepng.cpp.orig	Tue Nov  8 15:12:23 2011
+++ src/engine/IMG_savepng.cpp	Tue Nov  8 15:14:18 2011
@@ -30,6 +30,7 @@
  */
 #include <stdlib.h>
 #include "SDL.h"
+#include "zlib.h"
 #include "IMG_savepng.h"
 
 #ifdef WITH_IMAGE