diff --git a/packages/gatsby-plugin-offline/.gitignore b/packages/gatsby-plugin-offline/.gitignore
index 8c9686624a187..10cf84f0d2dc8 100644
--- a/packages/gatsby-plugin-offline/.gitignore
+++ b/packages/gatsby-plugin-offline/.gitignore
@@ -1,3 +1,4 @@
 /*.js
 !index.js
+!sw-append.js
 yarn.lock
diff --git a/packages/gatsby-plugin-offline/README.md b/packages/gatsby-plugin-offline/README.md
index 01ebf254e5d91..073aa58715007 100644
--- a/packages/gatsby-plugin-offline/README.md
+++ b/packages/gatsby-plugin-offline/README.md
@@ -40,12 +40,12 @@ const options = {
   cacheId: `gatsby-plugin-offline`,
   // Don't cache-bust JS or CSS files, and anything in the static directory,
   // since these files have unique URLs and their contents will never change
-  dontCacheBustUrlsMatching: /(\.js$|\.css$|\/static\/)/,
+  dontCacheBustUrlsMatching: /(\.js$|\.css$|static\/)/,
   runtimeCaching: [
     {
       // Use cacheFirst since these don't need to be revalidated (same RegExp
       // and same reason as above)
-      urlPattern: /(\.js$|\.css$|\/static\/)/,
+      urlPattern: /(\.js$|\.css$|static\/)/,
       handler: `cacheFirst`,
     },
     {
diff --git a/packages/gatsby-plugin-offline/src/gatsby-node.js b/packages/gatsby-plugin-offline/src/gatsby-node.js
index c522b426b51f1..4d014c439ed8a 100644
--- a/packages/gatsby-plugin-offline/src/gatsby-node.js
+++ b/packages/gatsby-plugin-offline/src/gatsby-node.js
@@ -82,12 +82,12 @@ exports.onPostBuild = (args, pluginOptions) => {
     cacheId: `gatsby-plugin-offline`,
     // Don't cache-bust JS or CSS files, and anything in the static directory,
     // since these files have unique URLs and their contents will never change
-    dontCacheBustUrlsMatching: /(\.js$|\.css$|\/static\/)/,
+    dontCacheBustUrlsMatching: /(\.js$|\.css$|static\/)/,
     runtimeCaching: [
       {
         // Use cacheFirst since these don't need to be revalidated (same RegExp
         // and same reason as above)
-        urlPattern: /(\.js$|\.css$|\/static\/)/,
+        urlPattern: /(\.js$|\.css$|static\/)/,
         handler: `cacheFirst`,
       },
       {
@@ -126,7 +126,7 @@ exports.onPostBuild = (args, pluginOptions) => {
         .readFileSync(`${__dirname}/sw-append.js`, `utf8`)
         .replace(/%pathPrefix%/g, pathPrefix)
 
-      fs.appendFileSync(`public/sw.js`, swAppend)
+      fs.appendFileSync(`public/sw.js`, `\n` + swAppend)
       console.log(
         `Generated ${swDest}, which will precache ${count} files, totaling ${size} bytes.`
       )
diff --git a/packages/gatsby-plugin-offline/src/sw-append.js b/packages/gatsby-plugin-offline/sw-append.js
similarity index 100%
rename from packages/gatsby-plugin-offline/src/sw-append.js
rename to packages/gatsby-plugin-offline/sw-append.js