diff --git a/websocket-sharp/Server/WebSocketServer.cs b/websocket-sharp/Server/WebSocketServer.cs
index f9ab97a8..2cede096 100644
--- a/websocket-sharp/Server/WebSocketServer.cs
+++ b/websocket-sharp/Server/WebSocketServer.cs
@@ -629,10 +629,17 @@ namespace WebSocketSharp.Server
     /// Gets or sets the wait time for the response to
     /// the WebSocket Ping or Close.
     /// </summary>
+    /// <remarks>
+    /// The set operation does nothing if the server has already
+    /// started or it is shutting down.
+    /// </remarks>
     /// <value>
     /// A <see cref="TimeSpan"/> that represents the wait time for
     /// the response. The default value is the same as 1 second.
     /// </value>
+    /// <exception cref="ArgumentException">
+    /// The value specified for a set operation is zero or less.
+    /// </exception>
     public TimeSpan WaitTime {
       get {
         return _services.WaitTime;