diff --git a/tox.ini b/tox.ini
index 7453e216..bb2b217a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -26,11 +26,13 @@ deps =
     zope.interface
 commands =
     sphinx-build -W -b html -d {envtmpdir}/doctrees docs docs/_build/html
+    sphinx-build -W -b doctest -d {envtmpdir}/doctrees docs docs/_build/html
     python -m doctest README.rst
 
 
 [testenv:manifest]
 deps = check-manifest
+skip_install = true
 commands = check-manifest