diff --git a/tox.ini b/tox.ini
index 6ce934b766..0d4fbd7e5c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -119,6 +119,7 @@ basepython = python3
 deps =
   -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
+  -r{toxinidir}/requirements.txt
 commands = sphinx-build -W -b html doc/source doc/build/html
 
 [testenv:api-ref]