diff --git a/gdk/gdksurfaceprivate.h b/gdk/gdksurfaceprivate.h
index be587ade5e..eafdb78c19 100644
--- a/gdk/gdksurfaceprivate.h
+++ b/gdk/gdksurfaceprivate.h
@@ -41,7 +41,7 @@ struct _GdkSurface
   gint x;
   gint y;
 
-  guint8 surface_type;
+  GdkSurfaceType surface_type;
 
   guint8 resize_count;