diff --git a/tox.ini b/tox.ini
index 4e140b6..d08b3f9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -27,7 +27,7 @@ requires =
     pip>=21,!=22.2
     tox-envlist>=0.2.1
     tox~=3.0
-    virtualenv!=20.16.0
+    virtualenv!=20.16.0,<20.39
 
 [envlists]
 test = py37, py38, py39, py310, py311, py312, py313