diff --git a/polytope_server/common/datasource/polytope.py b/polytope_server/common/datasource/polytope.py
index fe07912..17c2fee 100644
--- a/polytope_server/common/datasource/polytope.py
+++ b/polytope_server/common/datasource/polytope.py
@@ -163,8 +163,8 @@ def change_hash(self, request, config):
         if request.get("dataset", None) == "extremes-dt":
             if request["levtype"] == "pl" and "130" in request["param"]:
                 if request["param"] != "130":
-                    raise (ValueError("""Parameter 130 is on a different grids than other parameters.
-                                      Please request it separately."""))
+                    raise ValueError("""Parameter 130 is on a different grids than other parameters.
+                                      Please request it separately.""")
                 hash = "1c409f6b78e87eeaeeb4a7294c28add7"
                 return self.change_config_grid_hash(config, hash)