diff --git a/tox.ini b/tox.ini
index 7afad97..ce3d254 100644
--- a/tox.ini
+++ b/tox.ini
@@ -43,7 +43,9 @@ commands =
     coverage report --fail-under=95 --skip-covered
 
 [testenv:docs]
-deps = -r{toxinidir}/doc/requirements.txt
+deps =
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} 
+  -r{toxinidir}/doc/requirements.txt
 whitelist_externals = rm
 commands =
   rm -rf doc/build doc/source/reference/modules