diff --git a/tox.ini b/tox.ini
index c6043d4..ee8ca03 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://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
+install_command = pip install -c{env:TOX_CONSTRAINTS_FILE:https://git.openstack.org/cgit/openstack/requirements/plain/upper-constraints.txt} {opts} {packages}
 setenv = VIRTUAL_ENV={envdir}
 passenv =
     CURL_CA_BUNDLE