diff --git a/docs/guide/extract-css.md b/docs/guide/extract-css.md
index 109e51923..7557392b7 100644
--- a/docs/guide/extract-css.md
+++ b/docs/guide/extract-css.md
@@ -33,7 +33,7 @@ module.exports = {
   plugins: [
     // ... Vue Loader plugin omitted
     new MiniCssExtractPlugin({
-      filename: style.css
+      filename: 'style.css'
     })
   ]
 }