diff --git a/examples/coffeescript/modules/coffeescript.js b/examples/coffeescript/modules/coffeescript.js
index c108c127b293..3dcc8dc83c10 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$/,
diff --git a/examples/pug-stylus-coffee/modules/coffeescript.js b/examples/pug-stylus-coffee/modules/coffeescript.js
index c108c127b293..3dcc8dc83c10 100644
--- a/examples/pug-stylus-coffee/modules/coffeescript.js
+++ b/examples/pug-stylus-coffee/modules/coffeescript.js
@@ -1,6 +1,6 @@
 export default function () {
   // Add .coffee extension for store, middleware and more
-  this.nuxt.options.extensions.push('coffee')
+  this.nuxt.options.build.additionalExtensions.push('coffee')
   // Extend build
   const coffeeLoader = {
     test: /\.coffee$/,
diff --git a/packages/builder/src/builder.js b/packages/builder/src/builder.js
index 8245090b358e..734231b5de78 100644
--- a/packages/builder/src/builder.js
+++ b/packages/builder/src/builder.js
@@ -44,7 +44,7 @@ export default class Builder {
       restart: null
     }
 
-    this.supportedExtensions = ['vue', 'js', ...(this.options.extensions || []), ...(this.options.build.additionalExtensions || [])]
+    this.supportedExtensions = ['vue', 'js', ...(this.options.build.additionalExtensions || [])]
 
     // Helper to resolve build paths
     this.relativeToBuild = (...args) => relativeTo(this.options.buildDir, ...args)