diff --git a/tox.ini b/tox.ini
index 8f1b1df..afbaf2b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -16,6 +16,7 @@
 
 [tox]
 envlist = lint, py36, py37, py38, py39, py310, py311
+requires = virtualenv<20.22.0
 
 [gh-actions]
 python =