diff -r e3bb87952c62 Lib/test/test_re.py
--- a/Lib/test/test_re.py	Wed Jun 15 01:05:27 2016 +0000
+++ b/Lib/test/test_re.py	Wed Jun 15 14:56:11 2016 +0800
@@ -388,22 +388,29 @@
                          [("a", ""),("b", "b"),("a", "")])
 
     def test_re_match(self):
+        class Zero:
+            def __index__(self):
+                return 0
+
         for string in 'a', S('a'):
             self.assertEqual(re.match('a', string).groups(), ())
             self.assertEqual(re.match('(a)', string).groups(), ('a',))
             self.assertEqual(re.match('(a)', string).group(0), 'a')
+            self.assertEqual(re.match('(a)', string).group(Zero()), 'a')
             self.assertEqual(re.match('(a)', string).group(1), 'a')
             self.assertEqual(re.match('(a)', string).group(1, 1), ('a', 'a'))
         for string in b'a', B(b'a'), bytearray(b'a'), memoryview(b'a'):
             self.assertEqual(re.match(b'a', string).groups(), ())
             self.assertEqual(re.match(b'(a)', string).groups(), (b'a',))
             self.assertEqual(re.match(b'(a)', string).group(0), b'a')
+            self.assertEqual(re.match(b'(a)', string).group(Zero()), b'a')
             self.assertEqual(re.match(b'(a)', string).group(1), b'a')
             self.assertEqual(re.match(b'(a)', string).group(1, 1), (b'a', b'a'))
         for a in ("\xe0", "\u0430", "\U0001d49c"):
             self.assertEqual(re.match(a, a).groups(), ())
             self.assertEqual(re.match('(%s)' % a, a).groups(), (a,))
             self.assertEqual(re.match('(%s)' % a, a).group(0), a)
+            self.assertEqual(re.match('(%s)' % a, a).group(Zero()), a)
             self.assertEqual(re.match('(%s)' % a, a).group(1), a)
             self.assertEqual(re.match('(%s)' % a, a).group(1, 1), (a, a))
 
@@ -417,7 +424,7 @@
         # A single group
         m = re.match('(a)', 'a')
         self.assertEqual(m.group(0), 'a')
-        self.assertEqual(m.group(0), 'a')
+        self.assertEqual(m.group(Zero()), 'a')
         self.assertEqual(m.group(1), 'a')
         self.assertEqual(m.group(1, 1), ('a', 'a'))
 
diff -r e3bb87952c62 Modules/_sre.c
--- a/Modules/_sre.c	Wed Jun 15 01:05:27 2016 +0000
+++ b/Modules/_sre.c	Wed Jun 15 14:56:11 2016 +0800
@@ -2049,8 +2049,8 @@
         /* Default value */
         return 0;
 
-    if (PyLong_Check(index))
-        return PyLong_AsSsize_t(index);
+    if (PyIndex_Check(index))
+        return PyNumber_AsSsize_t(index, PyExc_IndexError);
 
     i = -1;