diff --git a/Objects/weakrefobject.c b/Objects/weakrefobject.c
index e1f4bc4..c8b982f 100644
--- a/Objects/weakrefobject.c
+++ b/Objects/weakrefobject.c
@@ -271,7 +271,6 @@
 parse_weakref_init_args(char *funcname, PyObject *args, PyObject *kwargs,
                         PyObject **obp, PyObject **callbackp)
 {
-    /* XXX Should check that kwargs == NULL or is empty. */
     return PyArg_UnpackTuple(args, funcname, 1, 2, obp, callbackp);
 }
 
@@ -334,6 +333,9 @@
 {
     PyObject *tmp;
 
+    if (!_PyArg_NoKeywords("ref()", kwargs))
+        return -1;
+
     if (parse_weakref_init_args("__init__", args, kwargs, &tmp, &tmp))
         return 0;
     else