diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index 8b51a53..49c7d52 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2175,8 +2175,10 @@
 	PyTypeObject *base;
 	int i, n;
 
-	if (type->tp_flags & Py_TPFLAGS_READY)
+	if (type->tp_flags & Py_TPFLAGS_READY) {
+		assert(type->tp_dict != NULL);
 		return 0;
+	}
 	assert((type->tp_flags & Py_TPFLAGS_READYING) == 0);
 
 	type->tp_flags |= Py_TPFLAGS_READYING;