diff --git a/tox.ini b/tox.ini
index 74cf4ef3e..52f440dbf 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-minversion = 3.2.1
+minversion = 3.9.0
 envlist = py3,pep8
 skipsdist = True
 ignore_basepython_conflict=true