diff --git a/websocket-sharp/Server/WebSocketBehavior.cs b/websocket-sharp/Server/WebSocketBehavior.cs
index fe4d6fa7..248b4fbf 100644
--- a/websocket-sharp/Server/WebSocketBehavior.cs
+++ b/websocket-sharp/Server/WebSocketBehavior.cs
@@ -1521,13 +1521,15 @@ namespace WebSocketSharp.Server
     /// </exception>
     /// <exception cref="InvalidOperationException">
     ///   <para>
-    ///   The session has not started yet.
+    ///   The SendAsync method is not available when the session has not
+    ///   started yet.
     ///   </para>
     ///   <para>
     ///   -or-
     ///   </para>
     ///   <para>
-    ///   The current state of the WebSocket interface is not Open.
+    ///   The SendAsync method is not available when the current state of
+    ///   the WebSocket interface is not Open.
     ///   </para>
     /// </exception>
     protected void SendAsync (Stream stream, int length, Action<bool> completed)