diff --git a/app.js b/app.js
index 1a55405..4c1740f 100644
--- a/app.js
+++ b/app.js
@@ -217,7 +217,7 @@ global.syzoj = {
     app.use(Session(sessionConfig));
 
     app.use((req, res, next) => {
-      res.locals.useLocalLibs = !!parseInt(req.headers['syzoj-no-cdn']);
+      res.locals.useLocalLibs = !!parseInt(req.headers['syzoj-no-cdn']) || syzoj.config.no_cdn;
 
       let User = syzoj.model('user');
       if (req.session.user_id) {
diff --git a/config-example.json b/config-example.json
index f54885a..2c5a90b 100644
--- a/config-example.json
+++ b/config-example.json
@@ -120,5 +120,6 @@
   "google_fonts": {
     "type": "like-google-fonts",
     "url": "https://fonts.loli.net"
-  }
+  },
+  "no_cdn": false
 }