diff --git a/requirements/tox.txt b/requirements/tox.txt
index 6d2e32a..2a83b5e 100644
--- a/requirements/tox.txt
+++ b/requirements/tox.txt
@@ -4,4 +4,4 @@
 
 -r test.txt
 
-tox==3.21.1
+tox==3.21.4