diff -r 1b212e366b66 Lib/multiprocessing/reduction.py
--- a/Lib/multiprocessing/reduction.py	Sun Mar 06 16:50:44 2016 +0200
+++ b/Lib/multiprocessing/reduction.py	Mon Mar 07 20:56:20 2016 -0500
@@ -45,7 +45,7 @@
         cls._extra_reducers[type] = reduce
 
     @classmethod
-    def dumps(cls, obj, protocol=None):
+    def dumps(cls, obj, protocol=pickle.HIGHEST_PROTOCOL):
         buf = io.BytesIO()
         cls(buf, protocol).dump(obj)
         return buf.getbuffer()
@@ -54,7 +54,7 @@
 
 register = ForkingPickler.register
 
-def dump(obj, file, protocol=None):
+def dump(obj, file, protocol=pickle.HIGHEST_PROTOCOL):
     '''Replacement for pickle.dump() using ForkingPickler.'''
     ForkingPickler(file, protocol).dump(obj)