1 files changed, 1 insertions, 0 deletions

diff --git a/tox.ini b/tox.ini
index 9acdc699f..fd62ffa7b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -129,6 +129,7 @@ max-complexity=24
 [testenv:docs]
 basepython = python3
 deps =
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/stein}
   -r{toxinidir}/doc/requirements.txt
   .[ldap,memcache,mongodb]
 commands=