diff --git a/utils/utils.py b/utils/utils.py
index f023893c..f8f192b4 100755
--- a/utils/utils.py
+++ b/utils/utils.py
@@ -555,7 +555,7 @@ def non_max_suppression(prediction, conf_thres=0.1, iou_thres=0.6, multi_label=T
             i = torchvision.ops.boxes.nms(boxes, scores, iou_thres)
             iou = box_iou(boxes, boxes[i]).tril_()  # lower triangular iou matrix
             weights = (iou > iou_thres) * scores.view(-1, 1)
-            weights /= weights.sum(0)
+            weights /= weights.sum(0) + 1E-6
             x[i, :4] = torch.mm(weights.T, x[:, :4])  # merged_boxes(n,4) = weights(n,n) * boxes(n,4)
         elif method == 'vision':
             i = torchvision.ops.boxes.nms(boxes, scores, iou_thres)