diff --git a/README.md b/README.md
index 196455562..3a23aed9d 100644
--- a/README.md
+++ b/README.md
@@ -266,8 +266,10 @@ wss.on('connection', function connection(ws, request, client) {
 });
 
 server.on('upgrade', function upgrade(request, socket, head) {
+  // This function is not defined on purpose. Implement it with your own logic.
   authenticate(request, (err, client) => {
     if (err || !client) {
+      socket.write('HTTP/1.1 401 Unauthorized\r\n\r\n');
       socket.destroy();
       return;
     }