diff --git a/src/parseUtils.js b/src/parseUtils.js
index 5169c00f..48b7ceeb 100644
--- a/src/parseUtils.js
+++ b/src/parseUtils.js
@@ -7,8 +7,12 @@ module.exports = {
   parseBundle
 };
 
-function parseBundle(bundlePath) {
-  const content = fs.readFileSync(bundlePath, 'utf8');
+const defaultBundleHost = {
+  getFileContent: path => fs.readFileSync(path, 'utf8')
+};
+
+function parseBundle(bundlePath, bundleHost = defaultBundleHost) {
+  const content = bundleHost.getFileContent(bundlePath);
   const ast = acorn.parse(content, {
     sourceType: 'script',
     // I believe in a bright future of ECMAScript!
diff --git a/test/parseUtils.js b/test/parseUtils.js
index f863e689..970dbfbe 100644
--- a/test/parseUtils.js
+++ b/test/parseUtils.js
@@ -30,4 +30,16 @@ describe('parseBundle', function () {
     expect(bundle.src).to.equal(fs.readFileSync(bundleFile, 'utf8'));
     expect(bundle.modules).to.deep.equal({});
   });
+
+  it('should allow a custom bundle host to override file system operations', function () {
+    let getBundleContentArg;
+    const bundle = parseBundle('arg', {
+      getFileContent: bundlePath => {
+        getBundleContentArg = bundlePath;
+        return 'webpackJsonp([0],[(t,e,r)=>{}])';
+      }
+    });
+    expect(getBundleContentArg).to.equal('arg');
+    expect(bundle.modules).to.deep.equal({0: '(t,e,r)=>{}'});
+  });
 });