diff --git a/tox.ini b/tox.ini
index 27f96d8af..3186b1984 100644
--- a/tox.ini
+++ b/tox.ini
@@ -52,7 +52,8 @@ commands =
 
 [testenv:docs]
 basepython = python3
-deps = -r{toxinidir}/doc/requirements.txt
+deps = -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+       -r{toxinidir}/doc/requirements.txt
 commands = sphinx-build -W -b html doc/source doc/build/html
 
 [flake8]