diff --git a/pyroengine/vision.py b/pyroengine/vision.py
index 9bfb606..85d0f78 100644
--- a/pyroengine/vision.py
+++ b/pyroengine/vision.py
@@ -58,7 +58,7 @@ def __init__(self, model_folder="data", imgsz=1024, conf=0.15, iou=0, format="nc
                 self.format = "ncnn"
 
             elif format == "onnx":
-                model = f"yolov8s.onnx"
+                model = "yolov8s.onnx"
                 self.format = "onnx"
 
             model_path = os.path.join(model_folder, model)