diff --git a/tox.ini b/tox.ini
index 8d1caa91..8f902ca6 100644
--- a/tox.ini
+++ b/tox.ini
@@ -50,7 +50,8 @@ commands =
     coverage report
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+commands =
+  sphinx-build -a -W -E -b html doc/source doc/build/html
 
 [flake8]
 # E128 continuation line under-indented for visual indent