Add coveralls

diff --git a/.travis.yml b/.travis.yml
index 0512948..e1989ea 100644
--- a/.travis.yml
+++ b/.travis.yml

@@ -5,5 +5,7 @@
     - TOXENV=py33
     - TOXENV=py34
     - TOXENV=pypy
-install: pip install tox --use-mirrors
+install: pip install coveralls tox --use-mirrors
 script: tox
+after_success:
+    - coveralls

diff --git a/README.md b/README.md
index 4e1c31d..a58cc01 100644
--- a/README.md
+++ b/README.md

@@ -1,4 +1,5 @@
 [![Build Status](https://travis-ci.org/pre-commit/pre-commit-hooks.svg?branch=master)](https://travis-ci.org/pre-commit/pre-commit-hooks)
+[![Coverage Status](https://img.shields.io/coveralls/pre-commit/pre-commit-hooks.svg?branch=master)](https://coveralls.io/r/pre-commit/pre-commit-hooks)
 
 pre-commit-hooks
 ==========