diff --git a/README.md b/README.md
index 8c4334c..e0100d9 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,9 @@ There is also a dependency on [co](https://www.npmjs.com/package/co).
 
 In addition there is a peer dependency for [immutable.js](https://facebook.github.io/immutable-js/), if you want to use it.
 
+#### babel-polyfill
+You need the [babel-polyfill](https://babeljs.io/docs/usage/polyfill/) in your build configuration for this package to work.
+
 ### Description
 
 This package handles [OpenID-Connect](http://openid.net/connect/) authentication in [redux](http://redux.js.org/) apps. It enables redux apps to authenticate with an external OIDC authentication provider and handles the actions of the OpenID [implicit flow](http://openid.net/specs/openid-connect-implicit-1_0.html).