diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index aa2d9c5a..bea3ddf9 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -4,7 +4,7 @@ ci:
 repos:
 - repo: https://github.com/astral-sh/ruff-pre-commit
   # Ruff version.
-  rev: v0.8.6
+  rev: v0.9.9
   hooks:
     # Run the linter.
     # TODO fix the lint issues for the Jupyter notebooks
diff --git a/examples/hotelling_law/tests.py b/examples/hotelling_law/tests.py
index 3d5a25fe..7787fa8a 100644
--- a/examples/hotelling_law/tests.py
+++ b/examples/hotelling_law/tests.py
@@ -32,9 +32,9 @@ def test_decreasing_price_variance():
 
     df_model = model.datacollector.get_model_vars_dataframe()
 
-    assert check_slope(
-        df_model["Price Variance"], increasing=False
-    ), "The price variance should decrease over time."
+    assert check_slope(df_model["Price Variance"], increasing=False), (
+        "The price variance should decrease over time."
+    )
 
 
 def test_constant_price_variance():
@@ -53,6 +53,6 @@ def test_constant_price_variance():
 
     df_model = model.datacollector.get_model_vars_dataframe()
 
-    assert (
-        get_slope(df_model["Price Variance"]) == 0
-    ), "The price variance constant over time."
+    assert get_slope(df_model["Price Variance"]) == 0, (
+        "The price variance constant over time."
+    )