diff --git a/src/utils/str.py b/src/utils/str.py
index d9ca25f66..5f822e56f 100644
--- a/src/utils/str.py
+++ b/src/utils/str.py
@@ -478,15 +478,14 @@ def format(s, *args, **kwargs):
             return has(args.pop())
         elif char == 'L':
             t = args.pop()
-            if isinstance(t, list) or (sys.version_info[0] >= 3 and
-                    (isinstance(t, map) or isinstance(t, filter))):
-                return commaAndify(t)
-            elif isinstance(t, tuple) and len(t) == 2:
+            if isinstance(t, tuple) and len(t) == 2:
                 if not isinstance(t[0], list):
                     raise ValueError('Invalid list for %%L in format: %s' % t)
                 if not isinstance(t[1], basestring):
                     raise ValueError('Invalid string for %%L in format: %s' % t)
                 return commaAndify(t[0], And=t[1])
+            elif hasattr(t, '__iter__'):
+                return commaAndify(t)
             else:
                 raise ValueError('Invalid value for %%L in format: %s' % t)
         elif char == 'p':
diff --git a/test/test_utils.py b/test/test_utils.py
index debad420f..ab41ea404 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -539,6 +539,18 @@ class FormatTestCase(SupyTestCase):
                          'I have 3 kinds of fruit: '
                          'apples, oranges, and watermelon.')
 
+    def testPercentL(self):
+        self.assertIn(format('%L', {'apples', 'oranges', 'watermelon'}), {
+                         'apples, oranges, and watermelon',
+                         'oranges, apples, and watermelon',
+                         'apples, watermelon, and oranges',
+                         'oranges, watermelon, and apples',
+                         'watermelon, apples, and oranges',
+                         'watermelon, oranges, and apples'})
+
+        self.assertEqual(format('%L',
+            (['apples', 'oranges', 'watermelon'], 'or')),
+            'apples, oranges, or watermelon')
 class RingBufferTestCase(SupyTestCase):
     def testInit(self):
         self.assertRaises(ValueError, RingBuffer, -1)