diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index e04a430..5fc2708 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -21,7 +21,7 @@ Please update the [docs](README.md) accordingly so that there are no discrepanci
 ## Developing
 
 - `npm run test` run the jasmine and mocha tests
-- `npm run build` run webpack and bundle the source
+- `npm run build` run rollup and bundle the source
 - `npm run version` prepare the code for release
 
 Please don't include changes to `dist/` in your pull request. This should only be updated when releasing a new version.
diff --git a/sandbox/client.js b/sandbox/client.js
index 580a7b0..f091a88 100644
--- a/sandbox/client.js
+++ b/sandbox/client.js
@@ -1,4 +1,4 @@
-import axios from '../index';
+import axios from '../index.js';
 
 const URL = 'http://127.0.0.1:3000/api';
 const BODY = {
@@ -17,4 +17,4 @@ axios.get(URL, { params: BODY })
 // POST
 axios.post(URL, BODY)
   .then(handleSuccess)
-  .catch(handleFailure);
\ No newline at end of file
+  .catch(handleFailure);