diff --git a/tox.ini b/tox.ini
index 58bc409..a76e36c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,7 +16,7 @@ setenv =
   PYTHONDONTWRITEBYTECODE=1
   PYTHONWARNINGS=default::DeprecationWarning
 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}/test-requirements.txt
   -r{toxinidir}/requirements.txt
 commands =