diff --git a/tox.ini b/tox.ini
index 00984e0..68e7298 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,7 +5,7 @@ skipdist = True
 
 [testenv]
 usedevelop = True
-install_command = pip install -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
+install_command = pip install -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master} {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/test-requirements.txt
 whitelist_externals = bash