diff --git a/tox.ini b/tox.ini
index 092ac2e7..36718430 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-requires = virtualenv<20.22.0
+requires = virtualenv<21.0.0
 envlist = py27, py310
 
 [testenv]