diff --git a/graphics/nine_patch.h b/graphics/nine_patch.h
index b45c92f09e0..c79c66b7112 100644
--- a/graphics/nine_patch.h
+++ b/graphics/nine_patch.h
@@ -54,7 +54,7 @@ namespace Graphics {
 
 struct TransparentSurface;
 struct Surface;
-struct MacWindowManager;
+class MacWindowManager;
 
 struct NinePatchMark {
 	int offset;