diff --git a/README.md b/README.md
index 2f35b95..5b47570 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # ms
 
 [![Build Status](https://travis-ci.org/zeit/ms.svg?branch=master)](https://travis-ci.org/zeit/ms)
+[![XO code style](https://img.shields.io/badge/code_style-XO-5ed9c7.svg)](https://github.com/sindresorhus/xo)
 [![Slack Channel](https://zeit-slackin.now.sh/badge.svg)](https://zeit.chat/)
 
 Use this package to easily convert various time formats to milliseconds.