diff --git a/.gitignore b/.gitignore
index c49070f13..f1dc3167c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,6 +12,7 @@ TAGS
 .tags
 .tox
 .venv
+.coverage
 .DS_Store
 sphinx/pycode/Grammar*pickle
 distribute-*
diff --git a/tox.ini b/tox.ini
index 04c23580d..411c85ba3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -6,6 +6,7 @@ passenv = https_proxy http_proxy no_proxy
 deps=
     six
     pytest
+    pytest-cov
     html5lib
     mock
     enum34
@@ -14,7 +15,7 @@ setenv =
     SPHINX_TEST_TEMPDIR = {envdir}/testbuild
     PYTHONDONTWRITEBYTECODE = true
 commands=
-    {envpython} -Wall tests/run.py --ignore tests/py35 {posargs}
+    {envpython} -Wall tests/run.py --ignore tests/py35 --cov=sphinx {posargs}
     sphinx-build -q -W -b html -d {envtmpdir}/doctrees doc {envtmpdir}/html
 
 [testenv:pypy]
@@ -63,7 +64,7 @@ deps=
     typed_ast
     {[testenv]deps}
 commands=
-    {envpython} -Wall tests/run.py {posargs}
+    {envpython} -Wall tests/run.py --cov=sphinx {posargs}
     sphinx-build -q -W -b html -d {envtmpdir}/doctrees doc {envtmpdir}/html
 
 [testenv:mypy]