diff --git a/examples/coffeescript/modules/coffeescript.js b/examples/coffeescript/modules/coffeescript.js
index c108c127b2..3dcc8dc83c 100644
--- a/examples/coffeescript/modules/coffeescript.js
+++ b/examples/coffeescript/modules/coffeescript.js
@@ -1,6 +1,6 @@
 export default function () {
   // Add .coffee extension for store, middleware and more
-  this.nuxt.options.extensions.push('coffee')
+  this.nuxt.options.build.additionalExtensions.push('coffee')
   // Extend build
   const coffeeLoader = {
     test: /\.coffee$/,
diff --git a/examples/pug-stylus-coffee/modules/coffeescript.js b/examples/pug-stylus-coffee/modules/coffeescript.js
index b8ccfc05d5..3dcc8dc83c 100644
--- a/examples/pug-stylus-coffee/modules/coffeescript.js
+++ b/examples/pug-stylus-coffee/modules/coffeescript.js
@@ -1,6 +1,6 @@
 export default function () {
   // Add .coffee extension for store, middleware and more
-  this.nuxt.options.extensions.push('coffee')
+  this.nuxt.options.build.additionalExtensions.push('coffee')
   // Extend build
   const coffeeLoader = {
     test: /\.coffee$/,
@@ -10,7 +10,7 @@ export default function () {
     // Add CoffeeScruot loader
     config.module.rules.push(coffeeLoader)
     // Add .coffee extension in webpack resolve
-    if (config.resolve.extensions.indexOf('.coffee') === -1) {
+    if (!config.resolve.extensions.includes('.coffee')) {
       config.resolve.extensions.push('.coffee')
     }
   })