diff --git a/nginx-nodejs-redis/web/server.js b/nginx-nodejs-redis/web/server.js
index 145b624..ae1d6d5 100644
--- a/nginx-nodejs-redis/web/server.js
+++ b/nginx-nodejs-redis/web/server.js
@@ -1,4 +1,4 @@
-cost os = require('os');
+const os = require('os');
 const express = require('express');
 const app = express();
 const redis = require('redis');