diff --git a/pyproject.toml b/pyproject.toml
index 0f13fbd2..1660fa69 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -91,6 +91,7 @@ isort = "~=5.10"
 mypy = "==1.5.1"
 mypy-zope = "==1.0.1"
 towncrier = ">=18.6.0"
+tox = ">=4.15.0"
 types-opentracing = ">=2.4.2"
 types-pyOpenSSL = ">=24.0.0"
 typing-extensions = ">=3.7.4"