diff --git a/Lib/test/test_builtin.py b/Lib/test/test_builtin.py
index 0560045..2d3e1cc 100644
--- a/Lib/test/test_builtin.py
+++ b/Lib/test/test_builtin.py
@@ -541,7 +541,8 @@
         self.assertEqual(format(-3.1415e-104, ""), str(-3.1415e-104))
         self.assertEqual(format(object, ""), str(object))
 
-        #self.assertRaises(TypeError, format, H(), "")
+        # TypeError because self.__format__ returns the wrong type
+        self.assertRaises(TypeError, format, H(), "")
 
     def test_getattr(self):
         import sys
diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index 662acd3..47d7236 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -424,6 +424,10 @@
             def __format__(self, format_spec):
                 return 1.0
 
+        class I(datetime.date):
+            def __format__(self, format_spec):
+                return self.strftime(format_spec)
+
 
         self.assertEqual(''.format(), '')
         self.assertEqual('abc'.format(), 'abc')
@@ -504,9 +508,6 @@
         self.assertEqual('{0!r:}'.format('Hello'), "'Hello'")
         self.assertEqual('{0!r}'.format(F('Hello')), 'F(Hello)')
 
-        # XXX should pass, but currently don't
-        # format(object, "")
-
         # test fallback to object.__format__
         self.assertEqual('{0}'.format({}), '{}')
         self.assertEqual('{0}'.format([]), '[]')
@@ -518,6 +519,11 @@
         self.assertEqual('{0:>15s}'.format(G('data')), ' string is data')
         self.assertEqual('{0!s}'.format(G('data')), 'string is data')
 
+        self.assertEqual("{0:date: %Y-%m-%d}".format(I(year=2007,
+                                                       month=8,
+                                                       day=27)),
+                         "date: 2007-08-27")
+
         # string format specifiers
         self.assertEqual('{0:}'.format('a'), 'a')