diff --git a/tox.ini b/tox.ini
index 8f9eaf29..108f77cd 100644
--- a/tox.ini
+++ b/tox.ini
@@ -22,7 +22,8 @@ commands = flake8
 commands = python setup.py sdist {posargs}
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+commands =
+  sphinx-build -W -d doc/build/doctrees -b html doc/source/ doc/build/html
 
 [testenv:venv]
 commands = {posargs}