diff --git a/.zuul.yaml b/.zuul.yaml
index 435020c5da7..4730dd66e9b 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -1,4 +1,6 @@
 - project:
+    vars:
+      ensure_tox_version: '<4'
     templates:
       - openstack-python3-xena-jobs
       - openstack-python3-xena-jobs-arm64
diff --git a/tox.ini b/tox.ini
index 383ea3d2836..7ad4f0eb591 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,6 +1,8 @@
 [tox]
 minversion = 3.18.0
-requires = virtualenv>=20.4.2
+requires =
+    virtualenv>=20.4.2
+    tox<4
 skipsdist = True
 # python runtimes: https://governance.openstack.org/tc/reference/project-testing-interface.html#tested-runtimes
 envlist = py3,compliance,pep8