diff --git a/pyproject.toml b/pyproject.toml
index 50ea38c..5d5aa69 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,7 +29,7 @@ lxml = "^5.2.2"
 mypy = "^1.1"
 pytest = "^7.0.0" 
 pytest-cov = "^4.0.0" 
-tox = "^3.23.0"
+tox = ">=3.23,<5.0"
 ruff = ">=0.12,<0.16"
 
 [build-system]