diff --git a/darts/models/forecasting/forecasting_model.py b/darts/models/forecasting/forecasting_model.py
index 9a4ae89186..6634203762 100644
--- a/darts/models/forecasting/forecasting_model.py
+++ b/darts/models/forecasting/forecasting_model.py
@@ -1574,7 +1574,7 @@ def gridsearch(
             # list of instances of scikit-learn models, the behavior should work like
             # any argument passed to the Darts model."
             if isinstance(parameters["model"], dict):
-                if not "model_class" in parameters["model"]:
+                if "model_class" not in parameters["model"]:
                     raise_log(
                         ValueError(
                             "When the 'model' key is set as a dictionary, it must contain "