diff --git a/websocket-sharp/Server/HttpServer.cs b/websocket-sharp/Server/HttpServer.cs
index 48e5ecd0..8cf9985c 100644
--- a/websocket-sharp/Server/HttpServer.cs
+++ b/websocket-sharp/Server/HttpServer.cs
@@ -1459,7 +1459,7 @@ namespace WebSocketSharp.Server
     /// </remarks>
     /// <exception cref="InvalidOperationException">
     ///   <para>
-    ///   There is no server certificate for secure connections.
+    ///   There is no server certificate for secure connection.
     ///   </para>
     ///   <para>
     ///   -or-