diff -r fe813f5711a5 Lib/test/test_builtin.py
--- a/Lib/test/test_builtin.py	Thu Jun 09 10:00:42 2011 -0500
+++ b/Lib/test/test_builtin.py	Thu Jun 09 15:46:48 2011 -0400
@@ -317,7 +317,14 @@
         f = Foo()
         self.assertTrue(dir(f) == ["ga", "kan", "roo"])
 
-        # dir(obj__dir__not_list)
+        # dir(obj_using __dir__nonlist_sequence)
+        class Foo(object):
+            def __dir__(self):
+                return ('xyz', 'pdq', 'lmno')
+        f = Foo()
+        self.assertTrue(dir(f) == ['lmno', 'pdq', 'xyz'])
+
+        # dir(obj__dir__not_sequence)
         class Foo(object):
             def __dir__(self):
                 return 7
diff -r fe813f5711a5 Objects/object.c
--- a/Objects/object.c	Thu Jun 09 10:00:42 2011 -0500
+++ b/Objects/object.c	Thu Jun 09 15:46:48 2011 -0400
@@ -1907,6 +1907,7 @@
     PyObject *result = NULL;
     static PyObject *dir_str = NULL;
     PyObject *dirfunc;
+    PyObject *oldresult;
 
     assert(obj);
     if (PyInstance_Check(obj)) {
@@ -1940,13 +1941,10 @@
             return NULL;
 
         /* result must be a list */
-        /* XXX(gbrandl): could also check if all items are strings */
         if (!PyList_Check(result)) {
-            PyErr_Format(PyExc_TypeError,
-                         "__dir__() must return a list, not %.200s",
-                         Py_TYPE(result)->tp_name);
-            Py_DECREF(result);
-            result = NULL;
+            oldresult = result;
+            result = PySequence_List(result);
+            Py_DECREF(oldresult);
         }
     }