diff --git a/tox.ini b/tox.ini
index 3eb2c0d..f13f95c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -31,7 +31,10 @@ commands = {posargs}
 
 [testenv:docs]
 basepython = python3
-commands = python setup.py build_sphinx
+whitelist_externals = rm
+commands =
+    rm -fr doc/build
+    sphinx-build -W -b html doc/source doc/build/html {posargs}
 
 [testenv:cover]
 basepython = python3