diff --git a/requirements.txt b/requirements.txt
index b033e72..3105bc5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,3 @@
 domdf-python-tools>=2.8.1
 pytest>=6.2.2
-tox<4,>=3.23.0
+tox<5,>=3.23.0