diff --git a/tox.ini b/tox.ini
index ecd5dad2e..6a05c400d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -25,7 +25,7 @@ commands =
 commands = {posargs}
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+commands = sphinx-build -W -b html doc/source doc/build
 
 [testenv:validate]
 commands = python3 tools/validate_tags.py