python-2 spelling is assertRaisesRegexp
diff --git a/docs/index.txt b/docs/index.txt
index 5ed2d8b..3a321ed 100644
--- a/docs/index.txt
+++ b/docs/index.txt
@@ -144,6 +144,8 @@
 
 - f-strings need to be rewritten using some other string substitution.
 
+- ``assertRaisesRegex`` needs to be ``assertRaisesRegexp`` for Python 2.
+
 Backporting process
 -------------------
 
diff --git a/mock/tests/testmock.py b/mock/tests/testmock.py
index 9b4ee7e..a61dff1 100644
--- a/mock/tests/testmock.py
+++ b/mock/tests/testmock.py
@@ -437,7 +437,7 @@
         m = Mock()
         m(1)
         m(2)
-        self.assertRaisesRegex(AssertionError,
+        self.assertRaisesRegexp(AssertionError,
             re.escape("Calls: [call(1), call(2)]"),
             lambda: m.assert_called_once_with(2))
 
@@ -1326,7 +1326,7 @@
     def test_assert_not_called_message(self):
         m = Mock()
         m(1, 2)
-        self.assertRaisesRegex(AssertionError,
+        self.assertRaisesRegexp(AssertionError,
             re.escape("Calls: [call(1, 2)]"),
             m.assert_not_called)
 
@@ -1355,7 +1355,7 @@
         m = Mock()
         m(1, 2)
         m(3)
-        self.assertRaisesRegex(AssertionError,
+        self.assertRaisesRegexp(AssertionError,
             re.escape("Calls: [call(1, 2), call(3)]"),
             m.assert_called_once)