diff --git a/craft_utils.py b/craft_utils.py
index 43c1357..509c962 100755
--- a/craft_utils.py
+++ b/craft_utils.py
@@ -236,7 +236,7 @@ def getDetBoxes(textmap, linkmap, text_threshold, link_threshold, low_text, poly
 
 def adjustResultCoordinates(polys, ratio_w, ratio_h, ratio_net = 2):
     if len(polys) > 0:
-        polys = np.array(polys)
+        polys = np.array(polys, dtype=object)
         for k in range(len(polys)):
             if polys[k] is not None:
                 polys[k] *= (ratio_w * ratio_net, ratio_h * ratio_net)