diff --git a/yolo/model/yolo.py b/yolo/model/yolo.py
index 8d463c1..1252916 100644
--- a/yolo/model/yolo.py
+++ b/yolo/model/yolo.py
@@ -142,7 +142,7 @@ def save_load_weights(self, weights: Union[Path, OrderedDict]):
             if weights_key not in weights:  #.ckpt
                 weights_key = "model." + model_key
             if weights_key not in weights:  #.pt old
-                weights_key = model_key.removeprefix("model.")
+                weights_key = model_key[6:]
             if weights_key not in weights:
                 error_dict["Not Found"].add(tuple(model_key.split(".")[:-2]))
                 continue