diff --git a/yolov3/modeling.py b/yolov3/modeling.py
index 9cba02e4d9ad09180c0d5c5e6b75d0efa4401102..6bd9b9f1d76f3d0e8a1c1c970908c96fcdbc0454 100644
--- a/yolov3/modeling.py
+++ b/yolov3/modeling.py
@@ -272,6 +272,7 @@ class YoloLoss(fluid.dygraph.Layer):
         downsample = 32
         losses = []
 
+        # YOLOv3 output fields is different between 'train' and 'eval' mode
         if len(inputs) == 6:
             output1, output2, output3, gt_box, gt_label, gt_score = inputs
         elif len(inputs) == 8: