diff --git a/websocket-sharp/Net/HttpListener.cs b/websocket-sharp/Net/HttpListener.cs
index 5d5bac03..2758617d 100644
--- a/websocket-sharp/Net/HttpListener.cs
+++ b/websocket-sharp/Net/HttpListener.cs
@@ -558,6 +558,13 @@ namespace WebSocketSharp.Net
       _disposed = true;
     }
 
+    private string getRealm ()
+    {
+      var realm = _realm;
+
+      return realm != null && realm.Length > 0 ? realm : _defaultRealm;
+    }
+
     #endregion
 
     #region Internal Methods