fix typo #4904
diff --git a/Lib/pickle.py b/Lib/pickle.py
index 201dc99..2947bd4 100644
--- a/Lib/pickle.py
+++ b/Lib/pickle.py
@@ -830,7 +830,7 @@
         return k
 
     def persistent_load(self, pid):
-        raise UnpickingError("unsupported persistent id encountered")
+        raise UnpicklingError("unsupported persistent id encountered")
 
     dispatch = {}