diff --git a/src/lib/utils/ddd_utils.py b/src/lib/utils/ddd_utils.py
index 4f0c5949f..6a0c38fee 100644
--- a/src/lib/utils/ddd_utils.py
+++ b/src/lib/utils/ddd_utils.py
@@ -54,13 +54,13 @@ def draw_box_3d(image, corners, c=(0, 0, 255)):
   for ind_f in range(3, -1, -1):
     f = face_idx[ind_f]
     for j in range(4):
-      cv2.line(image, (corners[f[j], 0], corners[f[j], 1]),
-               (corners[f[(j+1)%4], 0], corners[f[(j+1)%4], 1]), c, 2, lineType=cv2.LINE_AA)
+      cv2.line(image, (int(corners[f[j], 0]), int(corners[f[j], 1])),
+               (int(corners[f[(j+1)%4], 0]), int(corners[f[(j+1)%4], 1])), c, 2, lineType=cv2.LINE_AA)
     if ind_f == 0:
-      cv2.line(image, (corners[f[0], 0], corners[f[0], 1]),
-               (corners[f[2], 0], corners[f[2], 1]), c, 1, lineType=cv2.LINE_AA)
-      cv2.line(image, (corners[f[1], 0], corners[f[1], 1]),
-               (corners[f[3], 0], corners[f[3], 1]), c, 1, lineType=cv2.LINE_AA)
+      cv2.line(image, (int(corners[f[0], 0]), int(corners[f[0], 1])),
+               (int(corners[f[2], 0]), int(corners[f[2], 1])), c, 1, lineType=cv2.LINE_AA)
+      cv2.line(image, (int(corners[f[1], 0]), int(corners[f[1], 1])),
+               (int(corners[f[3], 0]), int(corners[f[3], 1])), c, 1, lineType=cv2.LINE_AA)
   return image
 
 def unproject_2d_to_3d(pt_2d, depth, P):
@@ -128,4 +128,4 @@ def project_3d_bbox(location, dim, rotation_y, calib):
   ct = (tl + br) / 2
   rotation_y = 0.01
   print('alpha2rot_y', alpha2rot_y(alpha, ct[0], calib[0, 2], calib[0, 0]))
-  print('rotation_y', rotation_y)
\ No newline at end of file
+  print('rotation_y', rotation_y)