diff --git a/src/plugins/plugin_xep_0050.py b/src/plugins/plugin_xep_0050.py
index 55848417..5f83f16d 100644
--- a/src/plugins/plugin_xep_0050.py
+++ b/src/plugins/plugin_xep_0050.py
@@ -75,7 +75,7 @@ class AdHocError(Exception):
         """ Error to be used from callback
         @param error_const: one of XEP_0050.ERROR
         """
-        assert(error_const in XEP_0050.ERROR)
+        assert error_const in XEP_0050.ERROR
         self.callback_error = error_const
 
 class AdHocCommand(XMPPHandler):