diff --git a/tox.ini b/tox.ini
index 23bbb59..df22315 100644
--- a/tox.ini
+++ b/tox.ini
@@ -23,6 +23,9 @@ commands = flake8
 [testenv:docs]
 basepython = python3
 envdir = {toxworkdir}/venv
+deps =
+  -c{env:UPPER_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt}
+  -r{toxinidir}/doc/requirements.txt
 commands = python setup.py build_sphinx
 
 [flake8]