2.7 -> 3.1 versionchanges.
diff --git a/Doc/library/unittest.rst b/Doc/library/unittest.rst
index b7fb279..675114a 100644
--- a/Doc/library/unittest.rst
+++ b/Doc/library/unittest.rst
@@ -863,7 +863,7 @@
       This signals a test failure if *expr1* and *expr2* don't evaluate to the same
       object.
 
-      .. versionadded:: 2.7
+      .. versionadded:: 3.1
 
 
    .. method:: assertIsNot(expr1, expr2[, msg])
@@ -872,7 +872,7 @@
       This signals a test failure if *expr1* and *expr2* evaluate to the same
       object.
 
-      .. versionadded:: 2.7
+      .. versionadded:: 3.1
 
 
    .. method:: assertFalse(expr[, msg])