Index: Lib/pstats.py
===================================================================
--- Lib/pstats.py	(revision 59136)
+++ Lib/pstats.py	(working copy)
@@ -512,7 +512,7 @@
         new_callers[func] = caller
     for func, caller in source.iteritems():
         if func in new_callers:
-            new_callers[func] = caller + new_callers[func]
+            new_callers[func] = tuple([i[0] + i[1] for i in zip(caller, new_callers[func])])
         else:
             new_callers[func] = caller
     return new_callers