diff --git a/tox.ini b/tox.ini
index 900795597..96e4293a2 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,7 +14,9 @@ passenv = *_proxy,*_PROXY
 commands = {posargs}
 
 [testenv:docs]
-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 -b html doc/source doc/build/html