More codestring -> codebytes.
diff --git a/Lib/test/test_urllib2.py b/Lib/test/test_urllib2.py
index c8be440..39ec498 100644
--- a/Lib/test/test_urllib2.py
+++ b/Lib/test/test_urllib2.py
@@ -1050,7 +1050,7 @@
         self.assertFalse(http_handler.requests[0].has_header(auth_header))
         userpass = bytes('%s:%s' % (user, password), "ascii")
         auth_hdr_value = ('Basic ' +
-            base64.encodestring(userpass).strip().decode())
+            base64.encodebytes(userpass).strip().decode())
         self.assertEqual(http_handler.requests[1].get_header(auth_header),
                          auth_hdr_value)