diff --git a/tox.ini b/tox.ini
index 59764db..640880d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,7 +24,7 @@
 commands = {posargs}
 
 [testenv:docs]
-commands = python setup.py build_sphinx
+commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:releasenotes]
 commands =