diff --git a/pyproject.toml b/pyproject.toml
index 542cb6d..f16681c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -101,7 +101,7 @@ dev-pytest = [
   "pytest-mock == 3.15.1",
   "pytest-asyncio == 1.3.0",
   "async-solipsism == 0.9",
-  "deepdiff == 8.6.2",
+  "deepdiff == 9.0.0",
 ]
 dev = [
   "frequenz-client-electricity-trading[dev-mkdocs,dev-flake8,dev-formatting,dev-mkdocs,dev-mypy,dev-noxfile,dev-pylint,dev-pytest]",