diff --git a/docs/modules/workbox.md b/docs/modules/workbox.md
index fe788714..654e9465 100644
--- a/docs/modules/workbox.md
+++ b/docs/modules/workbox.md
@@ -58,6 +58,10 @@ workbox: {
 
 (String) Loads and inserts the contents of the specified file path into the service worker script, below autogenerated calls to `workbox.routing.*`. You may add as many extra calls as you want to this file.
 
+### `workboxExtensions`
+
+(String) Loads and inserts the contents of the specified file path into the service worker script before any call to `precacheAndRoute`. You may add as many extra calls as you want to this file.
+
 ### `clientsClaim`
 
 (Boolean) Start controlling any existing clients as soon as it activates. Enabled by default.
@@ -102,6 +106,7 @@ workbox: {
 
 (String) Defaults to `routerBase`.
 
+
 ## Examples
 
 ### Adding custom runtimeCaching items (For CDN)
@@ -234,3 +239,5 @@ workbox.routing.registerRoute(
 ```
 
 Thanks to [@CarterLi](https://github.com/CarterLi) for the tip.
+
+### Enable
diff --git a/packages/workbox/lib/module.js b/packages/workbox/lib/module.js
index 8d041942..feee8823 100755
--- a/packages/workbox/lib/module.js
+++ b/packages/workbox/lib/module.js
@@ -27,8 +27,9 @@ module.exports = function nuxtWorkbox (moduleOptions) {
         fileName: options.swDest,
         options: {
           ...options,
-          routingExtensions: readJSFiles(options.routingExtensions),
-          cachingExtensions: readJSFiles(options.cachingExtensions)
+          routingExtensions: readJSFiles.call(this, options.routingExtensions),
+          cachingExtensions: readJSFiles.call(this, options.cachingExtensions),
+          workboxExtensions: readJSFiles.call(this, options.workboxExtensions)
         }
       })
     }
diff --git a/packages/workbox/lib/utils.js b/packages/workbox/lib/utils.js
index 5e8c0786..1ff442c7 100644
--- a/packages/workbox/lib/utils.js
+++ b/packages/workbox/lib/utils.js
@@ -2,9 +2,8 @@ const { readFileSync, existsSync } = require('fs')
 
 function readJSFiles (files) {
   return Array.from(files)
-    .map(Boolean)
     .map(path => {
-      path = this.nuxt.resolveAlias(path)
+      path = this.nuxt.resolver.resolvePath(path)
       if (path && existsSync(path)) {
         return readFileSync(path, 'utf8')
       } else {
diff --git a/packages/workbox/templates/sw.js b/packages/workbox/templates/sw.js
index 38c9c6c8..f834ec36 100644
--- a/packages/workbox/templates/sw.js
+++ b/packages/workbox/templates/sw.js
@@ -24,6 +24,11 @@ workbox.skipWaiting()
 workbox.googleAnalytics.initialize()
 <% } %>
 
+<% if (options.workboxExtensions) { %>
+// -- Start of workboxExtensions --
+<%= options.workboxExtensions %>// -- End of workboxExtensions --
+<% } %>
+
 // --------------------------------------------------
 // Precaches
 // --------------------------------------------------
@@ -46,8 +51,7 @@ workbox.precaching.precacheAndRoute(['<%= options.offlinePage %>'])
 // --------------------------------------------------
 <% if (options.cachingExtensions) { %>
 // -- Start of cachingExtensions --
-<%= options.cachingExtensions %>
-// -- End of cachingExtensions --
+<%= options.cachingExtensions %>// -- End of cachingExtensions --
 <% } %>
 
 // Register route handlers for runtimeCaching
@@ -63,6 +67,5 @@ workbox.routing.registerRoute(new RegExp('/.*'), ({event}) => {
 
 <% if (options.routingExtensions) { %>
 // -- Start of routingExtensions --
-<%= options.routingExtensions %>
-// -- End of routingExtensions --
+<%= options.routingExtensions %>// -- End of routingExtensions --
 <% } %>
diff --git a/test/__snapshots__/pwa.test.js.snap b/test/__snapshots__/pwa.test.js.snap
index 19a12eea..80f006cf 100644
--- a/test/__snapshots__/pwa.test.js.snap
+++ b/test/__snapshots__/pwa.test.js.snap
@@ -71,6 +71,10 @@ workbox.skipWaiting()
 // Enable offline Google Analytics tracking
 workbox.googleAnalytics.initialize()
 
+// -- Start of workboxExtensions --
+// Workbox Extension
+// -- End of workboxExtensions --
+
 // --------------------------------------------------
 // Precaches
 // --------------------------------------------------
@@ -85,9 +89,17 @@ workbox.precaching.precacheAndRoute([], {
 // Runtime Caching
 // --------------------------------------------------
 
+// -- Start of cachingExtensions --
+// Caching Extension
+// -- End of cachingExtensions --
+
 // Register route handlers for runtimeCaching
 workbox.routing.registerRoute(new RegExp('https://google.com/.*'), workbox.strategies.cacheFirst ({}), 'GET')
 workbox.routing.registerRoute(new RegExp('/_nuxt/(?!.*(__webpack_hmr|hot-update))'), workbox.strategies.cacheFirst ({}), 'GET')
 workbox.routing.registerRoute(new RegExp('^/(?!.*(__webpack_hmr|hot-update))'), workbox.strategies.networkFirst ({}), 'GET')
+
+// -- Start of routingExtensions --
+// Routing Extension
+// -- End of routingExtensions --
 "
 `;
diff --git a/test/fixture/nuxt.config.js b/test/fixture/nuxt.config.js
index 493052a3..d95bf86c 100644
--- a/test/fixture/nuxt.config.js
+++ b/test/fixture/nuxt.config.js
@@ -28,6 +28,15 @@ module.exports = {
     importScripts: [
       'custom-sw.js'
     ],
+    workboxExtensions: [
+      '~/sw/workbox'
+    ],
+    cachingExtensions: [
+      '~/sw/caching'
+    ],
+    routingExtensions: [
+      '~/sw/routing'
+    ],
     runtimeCaching: [
       {
         urlPattern: 'https://google.com/.*',
diff --git a/test/fixture/sw/caching.js b/test/fixture/sw/caching.js
new file mode 100644
index 00000000..cfd61f07
--- /dev/null
+++ b/test/fixture/sw/caching.js
@@ -0,0 +1 @@
+// Caching Extension
diff --git a/test/fixture/sw/routing.js b/test/fixture/sw/routing.js
new file mode 100644
index 00000000..14dd4146
--- /dev/null
+++ b/test/fixture/sw/routing.js
@@ -0,0 +1 @@
+// Routing Extension
diff --git a/test/fixture/sw/workbox.js b/test/fixture/sw/workbox.js
new file mode 100644
index 00000000..d00deacf
--- /dev/null
+++ b/test/fixture/sw/workbox.js
@@ -0,0 +1 @@
+// Workbox Extension