diff --git a/websocket-sharp/Server/WebSocketSessionManager.cs b/websocket-sharp/Server/WebSocketSessionManager.cs
index 188db488..e4d49bad 100644
--- a/websocket-sharp/Server/WebSocketSessionManager.cs
+++ b/websocket-sharp/Server/WebSocketSessionManager.cs
@@ -270,11 +270,19 @@ namespace WebSocketSharp.Server
     }
 
     /// <summary>
-    /// Gets the wait time for the response to the WebSocket Ping or Close.
+    /// Gets or sets the time to wait for the response to the WebSocket Ping or
+    /// Close.
     /// </summary>
+    /// <remarks>
+    /// The set operation does nothing if the service has already started or
+    /// it is shutting down.
+    /// </remarks>
     /// <value>
-    /// A <see cref="TimeSpan"/> that represents the wait time.
+    /// A <see cref="TimeSpan"/> to wait for the response.
     /// </value>
+    /// <exception cref="ArgumentOutOfRangeException">
+    /// The value specified for a set operation is zero or less.
+    /// </exception>
     public TimeSpan WaitTime {
       get {
         return _waitTime;