diff --git a/websocket-sharp/Server/WebSocketBehavior.cs b/websocket-sharp/Server/WebSocketBehavior.cs
index 175d4c14..50930033 100644
--- a/websocket-sharp/Server/WebSocketBehavior.cs
+++ b/websocket-sharp/Server/WebSocketBehavior.cs
@@ -159,7 +159,7 @@ namespace WebSocketSharp.Server
     ///   </para>
     /// </value>
     /// <exception cref="InvalidOperationException">
-    /// The session has not started yet.
+    /// The get operation is not available when the session has not started yet.
     /// </exception>
     protected WebSocketState ReadyState {
       get {