1 files changed, 3 insertions, 1 deletions
diff --git a/tox.ini b/tox.ini
index 95d07102d..dd55f21eb 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