diff --git a/tox.ini b/tox.ini
index 2ca6055256..adf425a1b1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -57,7 +57,9 @@ commands =
 [testenv:docs]
 whitelist_externals =
   rm
-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 =
   rm -rf doc/build
   sphinx-build -W --keep-going -b html doc/source doc/build/html