diff --git a/websocket-sharp/Ext.cs b/websocket-sharp/Ext.cs
index 1dfe3675..b08000fb 100644
--- a/websocket-sharp/Ext.cs
+++ b/websocket-sharp/Ext.cs
@@ -251,10 +251,11 @@ namespace WebSocketSharp
              : null;
     }
 
-    internal static string CheckIfValidPingData (this byte [] data)
+    internal static string CheckIfValidControlData (
+      this byte [] data, string paramName)
     {
       return data.Length > 125
-             ? "'message' length must be less."
+             ? String.Format ("'{0}' length must be less.", paramName)
              : null;
     }
 
diff --git a/websocket-sharp/Server/WebSocketService.cs b/websocket-sharp/Server/WebSocketService.cs
index 05cb26aa..d8c3c063 100644
--- a/websocket-sharp/Server/WebSocketService.cs
+++ b/websocket-sharp/Server/WebSocketService.cs
@@ -269,39 +269,6 @@ namespace WebSocketSharp.Server
     {
     }
 
-    /// <summary>
-    /// Sends a Ping to the client of the current <see cref="WebSocketService"/>
-    /// instance.
-    /// </summary>
-    /// <returns>
-    /// <c>true</c> if the current <see cref="WebSocketService"/> instance
-    /// receives a Pong from the client in a time; otherwise, <c>false</c>.
-    /// </returns>
-    protected bool Ping ()
-    {
-      return _websocket != null
-             ? _websocket.Ping ()
-             : false;
-    }
-
-    /// <summary>
-    /// Sends a Ping with the specified <paramref name="message"/> to the client
-    /// of the current <see cref="WebSocketService"/> instance.
-    /// </summary>
-    /// <returns>
-    /// <c>true</c> if the current <see cref="WebSocketService"/> instance
-    /// receives a Pong from the client in a time; otherwise, <c>false</c>.
-    /// </returns>
-    /// <param name="message">
-    /// A <see cref="string"/> that represents the message to send.
-    /// </param>
-    protected bool Ping (string message)
-    {
-      return _websocket != null
-             ? _websocket.Ping (message)
-             : false;
-    }
-
     /// <summary>
     /// Sends a binary <paramref name="data"/> to the client of the current
     /// <see cref="WebSocketService"/> instance.
diff --git a/websocket-sharp/Server/WebSocketServiceHostManager.cs b/websocket-sharp/Server/WebSocketServiceHostManager.cs
index 6e4c055d..36c55eed 100644
--- a/websocket-sharp/Server/WebSocketServiceHostManager.cs
+++ b/websocket-sharp/Server/WebSocketServiceHostManager.cs
@@ -672,7 +672,7 @@ namespace WebSocketSharp.Server
 
       byte [] data = null;
       var msg = _state.CheckIfStarted () ??
-                (data = Encoding.UTF8.GetBytes (message)).CheckIfValidPingData ();
+                (data = Encoding.UTF8.GetBytes (message)).CheckIfValidControlData ("message");
 
       if (msg != null) {
         _logger.Error (msg);
diff --git a/websocket-sharp/Server/WebSocketSessionManager.cs b/websocket-sharp/Server/WebSocketSessionManager.cs
index f5655cdb..9b20cad2 100644
--- a/websocket-sharp/Server/WebSocketSessionManager.cs
+++ b/websocket-sharp/Server/WebSocketSessionManager.cs
@@ -588,7 +588,7 @@ namespace WebSocketSharp.Server
 
       byte [] data = null;
       var msg = _state.CheckIfStarted () ??
-                (data = Encoding.UTF8.GetBytes (message)).CheckIfValidPingData ();
+                (data = Encoding.UTF8.GetBytes (message)).CheckIfValidControlData ("message");
 
       if (msg != null) {
         _logger.Error (msg);
diff --git a/websocket-sharp/WebSocket.cs b/websocket-sharp/WebSocket.cs
index ba88bd96..82817b75 100644
--- a/websocket-sharp/WebSocket.cs
+++ b/websocket-sharp/WebSocket.cs
@@ -1437,10 +1437,9 @@ namespace WebSocketSharp
       return Convert.ToBase64String (src);
     }
 
-    internal bool Ping (byte [] frameAsBytes, int timeOut)
+    internal bool Ping (byte [] frame, int millisecondsTimeout)
     {
-      return send (frameAsBytes) &&
-             _receivePong.WaitOne (timeOut);
+      return send (frame) && _receivePong.WaitOne (millisecondsTimeout);
     }
 
     // As server, used to broadcast
@@ -1806,8 +1805,8 @@ namespace WebSocketSharp
     /// Sends a Ping using the WebSocket connection.
     /// </summary>
     /// <returns>
-    /// <c>true</c> if the <see cref="WebSocket"/> instance receives a Pong in a time;
-    /// otherwise, <c>false</c>.
+    /// <c>true</c> if the <see cref="WebSocket"/> instance receives the Pong to
+    /// this Ping from the server in a time; otherwise, <c>false</c>.
     /// </returns>
     public bool Ping ()
     {
@@ -1817,14 +1816,15 @@ namespace WebSocketSharp
     }
 
     /// <summary>
-    /// Sends a Ping with the specified <paramref name="message"/> using the WebSocket connection.
+    /// Sends a Ping with the specified <paramref name="message"/> using the
+    /// WebSocket connection.
     /// </summary>
     /// <param name="message">
-    /// A <see cref="string"/> that contains a message to send.
+    /// A <see cref="string"/> that represents the message to send.
     /// </param>
     /// <returns>
-    /// <c>true</c> if the <see cref="WebSocket"/> instance receives a Pong in a time;
-    /// otherwise, <c>false</c>.
+    /// <c>true</c> if the <see cref="WebSocket"/> instance receives the Pong to
+    /// this Ping from the server in a time; otherwise, <c>false</c>.
     /// </returns>
     public bool Ping (string message)
     {
@@ -1832,7 +1832,7 @@ namespace WebSocketSharp
         return Ping ();
 
       var data = Encoding.UTF8.GetBytes (message);
-      var msg = data.CheckIfValidPingData ();
+      var msg = data.CheckIfValidControlData ("message");
       if (msg != null) {
         _logger.Error (msg);
         error (msg);