diff --git a/tox.ini b/tox.ini
index da879bf..5cb26a3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -13,7 +13,7 @@
    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}/requirements.txt
   -r{toxinidir}/test-requirements.txt