diff --git a/pyproject.toml b/pyproject.toml
index 17e099a..9401932 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -46,7 +46,7 @@ email = "floss@frequenz.com"
 [project.optional-dependencies]
 dev-flake8 = [
   "flake8 == 7.3.0",
-  "flake8-datetimez == 20.10.0",
+  "flake8-datetimez == 26.8.1",
   "flake8-docstrings == 1.7.0",
   "flake8-pyproject == 1.2.4",  # For reading the flake8 config from pyproject.toml
   "pydoclint == 0.9.1",