diff --git a/requirements_test.txt b/requirements_test.txt
index 6bc9feb..a775382 100644
--- a/requirements_test.txt
+++ b/requirements_test.txt
@@ -1,6 +1,6 @@
 # Used for testing
 mypy
 check-python-versions
-tox==3.27.1
+tox==4.21.1
 tox-current-env
 pytest
\ No newline at end of file