diff --git a/graph-lib/README.md b/graph-lib/README.md
index a2d13dc..5f033e0 100644
--- a/graph-lib/README.md
+++ b/graph-lib/README.md
@@ -1,4 +1,5 @@
 [![Build Status](https://travis-ci.org/jsmaniac/phc.png?branch=master)](https://travis-ci.org/jsmaniac/phc)
+[![Coverage Status](https://coveralls.io/repos/jsmaniac/cover/badge.svg?branch=master&service=github)](https://coveralls.io/github/jsmaniac/cover?branch=master)
 
 How to build this project
 =========================