diff --git a/lib/plugins/helper/js.js b/lib/plugins/helper/js.js
index d02d5d149c..c9750a65aa 100644
--- a/lib/plugins/helper/js.js
+++ b/lib/plugins/helper/js.js
@@ -38,7 +38,7 @@ function jsHelper(...args) {
     } else {
       // New syntax
       item.src = url_for.call(this, item.src);
-      if (!item.src.endsWith('.css')) item.src += '.css';
+      if (!item.src.endsWith('.js')) item.src += '.js';
       result += htmlTag('script', { ...item }, '') + '\n';
     }
   });