diff --git a/tox.ini b/tox.ini
index 38e90dd8..602ee965 100644
--- a/tox.ini
+++ b/tox.ini
@@ -30,6 +30,7 @@ commands = python setup.py test --coverage --testr-args='{posargs}'
 
 [testenv:docs]
 deps =
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/xena}
   -r{toxinidir}/doc/requirements.txt
 commands =
   sphinx-build -W -b html -d doc/build/doctrees doc/source doc/build/html