diff --git a/frappy/client/__init__.py b/frappy/client/__init__.py
index 7eb4160..0d4ddfc 100644
--- a/frappy/client/__init__.py
+++ b/frappy/client/__init__.py
@@ -261,7 +261,6 @@ class SecopClient(ProxyClient):
     """a general SECoP client"""
     reconnect_timeout = 10
     _running = False
-    _shutdown = None
     _rxthread = None
     _txthread = None
     _connthread = None