diff --git a/utils/utils.py b/utils/utils.py
index 0566bbda..d02c93ec 100755
--- a/utils/utils.py
+++ b/utils/utils.py
@@ -581,7 +581,7 @@ def kmeans_targets(path='./data/coco_64img.txt'):  # from utils.utils import *;
 # Plotting functions ---------------------------------------------------------------------------------------------------
 def plot_one_box(x, img, color=None, label=None, line_thickness=None):
     # Plots one bounding box on image img
-    tl = line_thickness or round(0.002 * max(img.shape[0:2])) + 1  # line thickness
+    tl = line_thickness or round(0.002 * (img.shape[0]+img.shape[1])/2) + 1  # line thickness
     color = color or [random.randint(0, 255) for _ in range(3)]
     c1, c2 = (int(x[0]), int(x[1])), (int(x[2]), int(x[3]))
     cv2.rectangle(img, c1, c2, color, thickness=tl)