diff --git a/tox.ini b/tox.ini
index e2876ad..bf5b3a7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,7 +11,7 @@ setenv =
    VIRTUAL_ENV={envdir}
    PYTHONWARNINGS=default::DeprecationWarning
 deps =
-  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
+  -c{env:TOX_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/zed}
   -r{toxinidir}/doc/requirements.txt
 
 [testenv:pep8]