diff --git a/Lib/multiprocessing/managers.py b/Lib/multiprocessing/managers.py
@@ -958,7 +958,7 @@ def MakeProxyType(name, exposed, _cache={}):


def AutoProxy(token, serializer, manager=None, authkey=None,
-              exposed=None, incref=True):
    '''
    Return an auto-proxy for `token`
    '''
@@ -978,7 +978,7 @@ def AutoProxy(token, serializer, manager=None, authkey=None,

    ProxyType = MakeProxyType('AutoProxy[%s]' % token.typeid, exposed)
    proxy = ProxyType(token, serializer, manager=manager, authkey=authkey,
-                      incref=incref)
    proxy._isauto = True
    return proxy