diff --git a/tox.ini b/tox.ini
index 31d5324..c397c8c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,7 +14,7 @@ setenv =
    OS_STDERR_CAPTURE=1
    OS_TEST_TIMEOUT=60
 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
 commands = stestr run {posargs}