diff --git a/tox.ini b/tox.ini
index 2af62dd3..c23e0b83 100644
--- a/tox.ini
+++ b/tox.ini
@@ -30,8 +30,8 @@ commands = {posargs}
 # This environment is called from CI scripts to test and publish
 # the API Ref and Docs to docs.openstack.org.
 whitelist_externals = rm
-deps =
-  -r{toxinidir}/doc/requirements.txt
+deps = -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+       -r{toxinidir}/doc/requirements.txt
 commands =
   rm -rf doc/build
   sphinx-build -W --keep-going -b html -d doc/build/doctrees doc/source doc/build/html