diff --git a/tox.ini b/tox.ini
index 5ec4ae9..9e3f45c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,7 +9,7 @@ basepython = python3
 usedevelop = True
 setenv = VIRTUAL_ENV={envdir}
 deps =
-  -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
   -r{toxinidir}/doc/requirements.txt
 
 [testenv:venv]