diff --git a/tox.ini b/tox.ini
index 07e3180..ebe1570 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,6 +10,7 @@
 setenv = VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
+       -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/xena}
 commands = stestr run --slowest {posargs}
 
 [testenv:pep8]