diff --git a/Lib/concurrent/futures/process.py b/Lib/concurrent/futures/process.py
@@ -495,7 +495,11 @@ def shutdown(self, wait=True):
        # To reduce the risk of opening too many files, remove references to
        # objects that use file descriptors.
        self._queue_management_thread = None
-        self._call_queue = None
        self._result_queue = None
        self._processes = None
    shutdown.__doc__ = _base.Executor.shutdown.__doc__