diff --git a/websocket-sharp/WebSocket.cs b/websocket-sharp/WebSocket.cs
index 59ae50b5..d2e5a399 100644
--- a/websocket-sharp/WebSocket.cs
+++ b/websocket-sharp/WebSocket.cs
@@ -2502,16 +2502,34 @@ namespace WebSocketSharp
     }
 
     /// <summary>
-    /// Accepts the WebSocket handshake request asynchronously.
+    /// Accepts the handshake request asynchronously.
     /// </summary>
     /// <remarks>
     ///   <para>
-    ///   This method does not wait for the accept to be complete.
+    ///   This method does not wait for the accept process to be complete.
     ///   </para>
     ///   <para>
-    ///   This method is not available in a client.
+    ///   This method does nothing if the handshake request has already been
+    ///   accepted.
     ///   </para>
     /// </remarks>
+    /// <exception cref="InvalidOperationException">
+    ///   <para>
+    ///   This instance is a client.
+    ///   </para>
+    ///   <para>
+    ///   -or-
+    ///   </para>
+    ///   <para>
+    ///   The close process is in progress.
+    ///   </para>
+    ///   <para>
+    ///   -or-
+    ///   </para>
+    ///   <para>
+    ///   The connection has already been closed.
+    ///   </para>
+    /// </exception>
     public void AcceptAsync ()
     {
       if (_client) {