diff --git a/Lib/test/pickletester.py b/Lib/test/pickletester.py
index 734f2a3..8479d43 100644
--- a/Lib/test/pickletester.py
+++ b/Lib/test/pickletester.py
@@ -1,5 +1,6 @@
 import unittest
 import pickle
+import cPickle
 import pickletools
 import copy_reg
 
@@ -7,8 +8,9 @@
 
 # Tests that try a number of pickle protocols should have a
 #     for proto in protocols:
-# kind of outer loop.  Bump the 3 to 4 if/when protocol 3 is invented.
-protocols = range(3)
+# kind of outer loop.
+assert pickle.HIGHEST_PROTOCOL == cPickle.HIGHEST_PROTOCOL == 2
+protocols = range(pickle.HIGHEST_PROTOCOL + 1)
 
 
 # Return True if opcode code appears in the pickle, else False.