diff --git a/websocket-sharp/Ext.cs b/websocket-sharp/Ext.cs
index 027a9b43..b868850f 100644
--- a/websocket-sharp/Ext.cs
+++ b/websocket-sharp/Ext.cs
@@ -185,14 +185,6 @@ namespace WebSocketSharp
       response.OutputStream.Close ();
     }
 
-    internal static void CloseWithAuthChallenge (
-      this HttpListenerResponse response, string challenge
-    )
-    {
-      response.Headers.InternalSet ("WWW-Authenticate", challenge, true);
-      response.Close (HttpStatusCode.Unauthorized);
-    }
-
     internal static byte[] Compress (this byte[] data, CompressionMethod method)
     {
       return method == CompressionMethod.Deflate