diff --git a/Objects/intobject.c b/Objects/intobject.c
index f504af7..9ffc295 100644
--- a/Objects/intobject.c
+++ b/Objects/intobject.c
@@ -1138,7 +1138,7 @@
 	0,					/* tp_setattro */
 	0,					/* tp_as_buffer */
 	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_CHECKTYPES |
-		Py_TPFLAGS_BASETYPE,		/* tp_flags */
+		Py_TPFLAGS_BASETYPE | Py_TPFLAGS_INT_SUBCLASS,	/* tp_flags */
 	int_doc,				/* tp_doc */
 	0,					/* tp_traverse */
 	0,					/* tp_clear */