diff --git a/tox.ini b/tox.ini
index 9e7c9dc..ae7674c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -82,6 +82,9 @@ commands =
 [testenv:docs]
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://opendev.org/openstack/requirements/raw/branch/master/upper-constraints.txt}
+  # zaqar-ui doc generated the module reference,
+  # so requirements.txt should be here to apply upper-constraints
+  -r{toxinidir}/requirements.txt
   -r{toxinidir}/doc/requirements.txt
 commands=
   sphinx-build -W -b html doc/source doc/build/html