diff --git a/websocket-sharp/Server/WebSocketServiceManager.cs b/websocket-sharp/Server/WebSocketServiceManager.cs
index a4dff536..707de74f 100644
--- a/websocket-sharp/Server/WebSocketServiceManager.cs
+++ b/websocket-sharp/Server/WebSocketServiceManager.cs
@@ -806,6 +806,7 @@ namespace WebSocketSharp.Server
     /// <exception cref="InvalidOperationException">
     /// The current state of the manager is not Start.
     /// </exception>
+    [Obsolete ("This method will be removed.")]
     public Dictionary<string, Dictionary<string, bool>> Broadping ()
     {
       if (_state != ServerState.Start) {