diff -r c13398566409 Lib/test/test_enumerate.py
--- a/Lib/test/test_enumerate.py	Wed Mar 12 12:41:44 2014 +0100
+++ b/Lib/test/test_enumerate.py	Wed Mar 12 15:49:53 2014 +0200
@@ -2,6 +2,7 @@
 import operator
 import sys
 import pickle
+import weakref
 
 from test import support
 
@@ -235,6 +236,27 @@
         for data in 'abc', range(5), tuple(enumerate('abc')), range(1,17,5):
             self.check_pickle(reversed(data), list(data)[::-1])
 
+    def test_weakref(self):
+        class Foo:
+            def __init__(self):
+                self.data = [1, 2, 3, 4]
+
+            def __len__(self):
+                return len(self.data)
+
+            def __getitem__(self, index):
+                return self.data[index]
+
+        foo = Foo()
+        proxy = weakref.proxy(foo)
+        self.assertEqual(list(reversed(proxy)),
+                         [4, 3, 2, 1])
+        del foo
+
+        with self.assertRaises(TypeError) as cm:
+            reversed(proxy)
+        self.assertEqual(str(cm.exception),
+                         "argument to reversed() was dereferenced")
 
 class EnumerateStartTestCase(EnumerateTestCase):
 
diff -r c13398566409 Objects/enumobject.c
--- a/Objects/enumobject.c	Wed Mar 12 12:41:44 2014 +0100
+++ b/Objects/enumobject.c	Wed Mar 12 15:49:53 2014 +0200
@@ -259,9 +259,20 @@
         return NULL;
 
     if (!PySequence_Check(seq)) {
-        PyErr_SetString(PyExc_TypeError,
-                        "argument to reversed() must be a sequence");
-        return NULL;
+        if (!PyWeakref_CheckProxy(seq)) {
+           PyErr_SetString(PyExc_TypeError,
+                          "argument to reversed() must be a sequence");
+           return NULL;
+       } 
+       else {
+           PyTypeObject *s = (PyTypeObject *) PyWeakref_GetObject(seq);
+           if ((PyObject *)s == Py_None) {
+              PyErr_SetString(PyExc_TypeError,
+                              "argument to reversed() was dereferenced");
+              return NULL;
+           } else
+              seq = s;
+         }
     }
 
     n = PySequence_Size(seq);