diff --git a/.gitignore b/.gitignore
index 9bf4f063..fb9baf35 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,3 +11,9 @@ _mailinglist
 .tox
 .cache/
 .idea/
+
+# Coverage reports
+htmlcov
+.coverage
+.coverage.*
+*,cover
diff --git a/tox.ini b/tox.ini
index 28942d3e..57725d0a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -4,11 +4,12 @@ envlist = {py26,py27,pypy}-{lowest,release,devel}{,-simplejson}, {py33,py34,py35
 
 
 [testenv]
+usedevelop=true
 commands =
-    py.test []
-
+    py.test [] --cov=flask --cov-report html
 deps=
     pytest
+    pytest-cov
     greenlet
 
     lowest: Werkzeug==0.7