diff --git a/taskflow/persistence/backends/impl_memory.py b/taskflow/persistence/backends/impl_memory.py
index d3ad18fa..2d4c5e09 100644
--- a/taskflow/persistence/backends/impl_memory.py
+++ b/taskflow/persistence/backends/impl_memory.py
@@ -32,7 +32,7 @@ class MemoryBackend(base.Backend):
     """A backend that writes logbooks, flow details, and task details to in
     memory dictionaries.
     """
-    def __init__(self, conf):
+    def __init__(self, conf=None):
         super(MemoryBackend, self).__init__(conf)
         self._log_books = {}
         self._flow_details = {}