diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -313,9 +313,9 @@
         # dir(obj_using __dir__)
         class Foo(object):
             def __dir__(self):
-                return ["kan", "ga", "roo"]
+                return ('xyz', 'pdq', 'lmno')
         f = Foo()
-        self.assertTrue(dir(f) == ["ga", "kan", "roo"])
+        self.assertTrue(dir(f) == ['lmno', 'pdq', 'xyz'])
 
         # dir(obj__dir__not_list)
         class Foo(object):
diff --git a/Objects/object.c b/Objects/object.c
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -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);
         }
     }