diff --git a/Lib/pickle.py b/Lib/pickle.py
index ebfde4f..6c1bcbe 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -38,8 +38,9 @@
 mdumps = marshal.dumps
 mloads = marshal.loads
 
-PicklingError = "pickle.PicklingError"
-UnpicklingError = "pickle.UnpicklingError"
+class PickleError(Exception): pass
+class PicklingError(PickleError): pass
+class UnpicklingError(PickleError): pass
 
 try:
     from org.python.core import PyStringMap