diff --git a/tox.ini b/tox.ini
index 8c4bfc4..0a0a2fa 100644
--- a/tox.ini
+++ b/tox.ini
@@ -39,9 +39,6 @@ commands =
 
 [testenv:docs]
 basepython = python3
-extras =
-    test
-    docs
 commands =
     sphinx-build -b html -d docs/_build/doctrees docs docs/_build/html
     sphinx-build -b doctest -d docs/_build/doctrees docs docs/_build/doctest
@@ -54,6 +51,7 @@ deps =
     zope.testrunner
 commands =
     coverage run -m zope.testrunner --test-path=src []
+    coverage run -a -m sphinx -b doctest -d {envdir}/.cache/doctrees docs {envdir}/.cache/doctest
     coverage html
     coverage report -m --fail-under=87