diff --git a/websocket-sharp/Net/EndPointManager.cs b/websocket-sharp/Net/EndPointManager.cs
index c12349d5..5ad7dfd6 100644
--- a/websocket-sharp/Net/EndPointManager.cs
+++ b/websocket-sharp/Net/EndPointManager.cs
@@ -171,7 +171,7 @@ namespace WebSocketSharp.Net
       if (lsnr.IsSecure ^ pref.IsSecure)
         return;
 
-      lsnr.RemovePrefix (pref, listener);
+      lsnr.RemovePrefix (pref);
     }
 
     #endregion