diff --git a/tox.ini b/tox.ini
index 318d788..e48f5ff 100644
--- a/tox.ini
+++ b/tox.ini
@@ -29,7 +29,7 @@ commands = {posargs}
 basepython = python3
 commands =
   rm -rf doc/build api-ref/build
-  python setup.py build_sphinx
+  sphinx-build -a -E -W -d doc/build/doctrees -b html doc/source doc/build/html
   sphinx-build -a -E -W -d doc/build/doctrees -b latex doc/source doc/build/pdf
   make -C doc/build/pdf
   sphinx-build -a -E -W -d api-ref/build/doctrees -b html api-ref/source api-ref/build/html
@@ -37,7 +37,7 @@ commands =
 [testenv:html]
 commands =
   rm -rf doc/build api-ref/build
-  python setup.py build_sphinx
+  sphinx-build -a -E -W -d doc/build/doctrees -b html doc/source doc/build/html
   sphinx-build -a -E -W -d api-ref/build/doctrees -b html api-ref/source api-ref/build/html
 
 [testenv:releasenotes]