diff --git a/pyproject.toml b/pyproject.toml
index 7e45ec466..45ed8fcc0 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -42,7 +42,7 @@ dependencies = [
 [project.optional-dependencies]
 dev = [
   "ruff",
-  "mypy==1.2.0",
+  "mypy==1.9.0",
   "types-PyYAML",
   "types-setuptools",
   "types-pytz",