diff --git a/tox.ini b/tox.ini
index 265efee..82a0eff 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,7 +1,7 @@
 [tox]
 minversion = 1.6
 skipsdist = True
-envlist = pep8
+envlist = py39,pep8
 
 [testenv]
 basepython = python3