diff --git a/tools/make_ctests b/tools/make_ctests
index 0a9d5caa03..196bd53cf5 100755
--- a/tools/make_ctests
+++ b/tools/make_ctests
@@ -25,6 +25,7 @@ cat <<EOF
 
 #include <stdio.h>
 #include <stdlib.h>
+#include "windef.h"
 #include "winbase.h"
 
 EOF