diff --git a/gdk/quartz/gdkwindow-quartz.c b/gdk/quartz/gdkwindow-quartz.c
index aa1049655f..d7b2f04747 100644
--- a/gdk/quartz/gdkwindow-quartz.c
+++ b/gdk/quartz/gdkwindow-quartz.c
@@ -2346,7 +2346,7 @@ gdk_quartz_window_set_functions (GdkWindow    *window,
 
   if (impl->toplevel)
     {
-      NSWindowStyleMask mask = [impl->toplevel styleMask];
+      NSUInteger mask = [impl->toplevel styleMask];
 
       if (min)
         mask = mask | NSMiniaturizableWindowMask;