Index: rts/System/LoadSave/LuaLoadSaveHandler.cpp
--- rts/System/LoadSave/LuaLoadSaveHandler.cpp.orig
+++ rts/System/LoadSave/LuaLoadSaveHandler.cpp
@@ -25,6 +25,9 @@
 #include "System/StringUtil.h"
 #include "System/SafeUtil.h"
 
+#ifdef __OpenBSD__
+	#include <zlib.h>
+#endif
 
 
 // Prefix for all files in the save file.
