diff --git a/tox.ini b/tox.ini
index b07fdaf..66d9e10 100644
--- a/tox.ini
+++ b/tox.ini
@@ -322,6 +322,7 @@
 [testenv:pep8]
 deps =
     -r{toxinidir}/test-requirements.txt
+    -c{env:UPPER_CONSTRAINTS_FILE:https://releases.openstack.org/constraints/upper/master}
     autopep8
 commands =
     autopep8 --exit-code --max-line-length=79 --experimental --diff -r tempest setup.py