diff --git a/.zuul.yaml b/.zuul.yaml
index e96674b47..dc34dbbe6 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -7,6 +7,8 @@
       - openstack/python-keystoneclient
     vars:
       tox_envlist: functional
+      devstack_localrc:
+        USE_PYTHON3: True
 
 - project:
     templates:
diff --git a/tox.ini b/tox.ini
index a78e10363..9582d707f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -50,6 +50,7 @@ basepython = python3
 commands = oslo_debug_helper -t keystoneclient/tests {posargs}
 
 [testenv:functional]
+basepython = python3
 setenv = {[testenv]setenv}
          OS_TEST_PATH=./keystoneclient/tests/functional
 passenv = OS_*