diff --git a/websocket-sharp/Net/HttpListener.cs b/websocket-sharp/Net/HttpListener.cs
index 01e0fccf..3393db6e 100644
--- a/websocket-sharp/Net/HttpListener.cs
+++ b/websocket-sharp/Net/HttpListener.cs
@@ -147,7 +147,9 @@ namespace WebSocketSharp.Net
     /// </exception>
     public AuthenticationSchemes AuthenticationSchemes {
       get {
-        CheckDisposed ();
+        if (_disposed)
+          throw new ObjectDisposedException (_objectName);
+
         return _authSchemes;
       }