diff -r 87dcd948dc74 Objects/typeobject.c
--- a/Objects/typeobject.c	Wed Feb 29 16:21:25 2012 -0800
+++ b/Objects/typeobject.c	Thu Mar 01 13:54:08 2012 +0100
@@ -594,7 +594,13 @@ type_dict(PyTypeObject *type, void *cont
         Py_INCREF(Py_None);
         return Py_None;
     }
-    return PyDictProxy_New(type->tp_dict);
+    if (PyFrozenDict_Check(type->tp_dict)) {
+        Py_INCREF(type->tp_dict);
+        return type->tp_dict;
+    }
+    else {
+        return PyDictProxy_New(type->tp_dict);
+    }
 }
 
 static PyObject *
@@ -1807,7 +1813,7 @@ subtype_setdict(PyObject *obj, PyObject 
                         "This object has no __dict__");
         return -1;
     }
-    if (value != NULL && !PyDict_Check(value)) {
+    if (value != NULL && !PyDict_Check(value) && !PyFrozenDict_Check(value)) {
         PyErr_Format(PyExc_TypeError,
                      "__dict__ must be set to a dictionary, "
                      "not a '%.200s'", Py_TYPE(value)->tp_name);
@@ -2349,7 +2355,15 @@ type_new(PyTypeObject *metatype, PyObjec
     /* Put the proper slots in place */
     fixup_slot_dispatchers(type);
 
-    Py_DECREF(dict);
+    Py_CLEAR(dict);
+
+    if (PyDict_GetItemString(type->tp_dict, "__final__")) {
+        dict = PyFrozenDict_Copy(type->tp_dict);
+        if (dict == NULL)
+            goto error;
+        Py_DECREF(type->tp_dict);
+        type->tp_dict = dict;
+    }
     return (PyObject *)type;
 
 error:
@@ -2451,7 +2465,7 @@ _PyType_Lookup(PyTypeObject *type, PyObj
         base = PyTuple_GET_ITEM(mro, i);
         assert(PyType_Check(base));
         dict = ((PyTypeObject *)base)->tp_dict;
-        assert(dict && PyDict_Check(dict));
+        assert(dict && (PyDict_Check(dict) || PyFrozenDict_Check(dict)));
         res = PyDict_GetItem(dict, name);
         if (res != NULL)
             break;
@@ -2635,7 +2649,7 @@ merge_class_dict(PyObject *dict, PyObjec
     PyObject *bases;
     _Py_IDENTIFIER(__bases__);
 
-    assert(PyDict_Check(dict));
+    assert(PyDict_Check(dict) || PyFrozenDict_Check(dict));
     assert(aclass);
 
     /* Merge in the type's dict (if any). */
@@ -3587,7 +3601,7 @@ object_dir(PyObject *self, PyObject *arg
         PyErr_Clear();
         dict = PyDict_New();
     }
-    else if (!PyDict_Check(dict)) {
+    else if (!PyDict_Check(dict) && !PyFrozenDict_Check(dict)) {
         Py_DECREF(dict);
         dict = PyDict_New();
     }
@@ -6114,7 +6128,7 @@ recurse_down_subclasses(PyTypeObject *ty
         assert(PyType_Check(subclass));
         /* Avoid recursing down into unaffected classes */
         dict = subclass->tp_dict;
-        if (dict != NULL && PyDict_Check(dict) &&
+        if (dict != NULL && (PyDict_Check(dict) || PyFrozenDict_Check(dict)) &&
             PyDict_GetItem(dict, name) != NULL)
             continue;
         if (update_subclasses(subclass, name, callback, data) < 0)