diff --git a/tox.ini b/tox.ini
index 2a28959..3c90dfe 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,7 +7,7 @@ skipsdist = True
 usedevelop = True
 install_command = pip install {opts} {packages}
 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}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = stestr run {posargs}