Index: gtk/gtk.override
===================================================================
--- gtk/gtk.override	(revision 2949)
+++ gtk/gtk.override	(working copy)
@@ -1168,7 +1168,7 @@
 static GSource *
 pygtk_main_watch_new(void)
 {
-    return g_source_new(&pygtk_main_watch_funcs, sizeof(GSource));
+    return g_source_new(&pygtk_main_watch_funcs, sizeof(PySignalWatchSource));
 }