diff --git a/menu_tools/object_performance/plotter.py b/menu_tools/object_performance/plotter.py
index 09bda959..ada63958 100755
--- a/menu_tools/object_performance/plotter.py
+++ b/menu_tools/object_performance/plotter.py
@@ -459,7 +459,7 @@ def _write_scalings_to_file(self, obj: Object, params: np.ndarray) -> None:
         )
         os.makedirs(fpath, exist_ok=True)
         a, b = params
-        with open(os.path.join(fpath, f"{str(obj)}.yaml"), "w") as f:
+        with open(os.path.join(fpath, str(obj) + ".yaml"), "w") as f:
             yaml.dump({"offset": float(a), "slope": float(b)}, f)
 
     def run(self):
diff --git a/menu_tools/utils/objects.py b/menu_tools/utils/objects.py
index bc15fe66..8f31fcf9 100644
--- a/menu_tools/utils/objects.py
+++ b/menu_tools/utils/objects.py
@@ -36,10 +36,6 @@ def __init__(
     def __str__(self) -> str:
         return f"{self.nano_obj_name}:{self.obj_id_name}:{self.eta_range}"
 
-    @property
-    def file_ext(self) -> str:
-        return str(self).replace(":", "_")
-
     @property
     def nano_obj_name(self) -> str:
         return self.object_key.split(":")[0]