1 files changed, 1 insertions, 0 deletions

diff --git a/tox.ini b/tox.ini
index d9b67ef11..5df49d45a 100644
--- a/tox.ini
+++ b/tox.ini
@@ -135,6 +135,7 @@ max-complexity=24
 [testenv:docs]
 basepython = python3
 deps =
+  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/train}
   -r{toxinidir}/doc/requirements.txt
   .[ldap,memcache,mongodb]
 commands=