diff --git a/websocket-sharp/Server/WebSocketBehavior.cs b/websocket-sharp/Server/WebSocketBehavior.cs
index 026b60a7..1746bbfd 100644
--- a/websocket-sharp/Server/WebSocketBehavior.cs
+++ b/websocket-sharp/Server/WebSocketBehavior.cs
@@ -106,7 +106,7 @@ namespace WebSocketSharp.Server
     /// <c>true</c> if the communication is possible; otherwise, <c>false</c>.
     /// </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 bool IsAlive {
       get {