diff --git a/websocket-sharp/Net/HttpListener.cs b/websocket-sharp/Net/HttpListener.cs
index 07d02a5c..0c9269a5 100644
--- a/websocket-sharp/Net/HttpListener.cs
+++ b/websocket-sharp/Net/HttpListener.cs
@@ -605,7 +605,15 @@ namespace WebSocketSharp.Net
     internal AuthenticationSchemes SelectAuthenticationScheme (HttpListenerRequest request)
     {
       var selector = _authSchemeSelector;
-      return selector != null ? selector (request) : _authSchemes;
+      if (selector == null)
+        return _authSchemes;
+
+      try {
+        return selector (request);
+      }
+      catch {
+        return AuthenticationSchemes.None;
+      }
     }
 
     internal void UnregisterContext (HttpListenerContext context)