diff --git a/tox.ini b/tox.ini
index 2e1e6b3..42ceb3b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -5,7 +5,7 @@
 
 [tox]
 envlist =
-    flake8, py35, py36, py37, py38
+    flake8, py35, py36, py37, py38, py39
 # Other valid evironments are:
 #   docs
 #   release