diff --git a/requirements/test.txt b/requirements/test.txt
index be2e9e3..fdd0d1c 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -2,4 +2,4 @@
 coverage==4.5.4
 pytest-cov==2.8.1
 pytest==5.2.1
-tox==3.14.0
+tox==4.21.1