diff --git a/src/include/window.h b/src/include/window.h
index 83d95b484..12f91eed1 100644
--- a/src/include/window.h
+++ b/src/include/window.h
@@ -59,7 +59,7 @@ typedef enum
 #define META_TYPE_WINDOW            (meta_window_get_type ())
 #define META_WINDOW(obj)            (G_TYPE_CHECK_INSTANCE_CAST ((obj), META_TYPE_WINDOW, MetaWindow))
 #define META_WINDOW_CLASS(klass)    (G_TYPE_CHECK_CLASS_CAST ((klass),  META_TYPE_WINDOW, MetaWindowClass))
-#define META_IS_WINDOW(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), META_WINDOW_TYPE))
+#define META_IS_WINDOW(obj)         (G_TYPE_CHECK_INSTANCE_TYPE ((obj), META_TYPE_WINDOW))
 #define META_IS_WINDOW_CLASS(klass) (G_TYPE_CHECK_CLASS_TYPE ((klass),  META_TYPE_WINDOW))
 #define META_WINDOW_GET_CLASS(obj)  (G_TYPE_INSTANCE_GET_CLASS ((obj),  META_TYPE_WINDOW, MetaWindowClass))