diff --git a/tox.ini b/tox.ini
index eecd16e..3c18fbf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -14,7 +14,7 @@
    OS_STDOUT_CAPTURE={env:OS_STDOUT_CAPTURE:true}
    OS_STDERR_CAPTURE={env:OS_STDERR_CAPTURE:true}
 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 --slowest {posargs}