diff --git a/docs/api/index.md b/docs/api/index.md
index f98a247..a2a23a0 100644
--- a/docs/api/index.md
+++ b/docs/api/index.md
@@ -143,10 +143,11 @@ http.createServer(app.callback()).listen(3000);
 
 ```js
 const http = require('http');
+const https = require('https');
 const Koa = require('koa');
 const app = new Koa();
 http.createServer(app.callback()).listen(3000);
-http.createServer(app.callback()).listen(3001);
+https.createServer(app.callback()).listen(3001);
 ```
 
 ## app.callback()