diff --git a/model_server/base/roiset.py b/model_server/base/roiset.py
index 6ef46ed0779e306d0b6b1e4137f065f394d21e57..7cd327ae2403509a5486af4eb145a6514e62dcdd 100644
--- a/model_server/base/roiset.py
+++ b/model_server/base/roiset.py
@@ -294,7 +294,7 @@ class RoiSet(object):
                 mask_largest_object(
                     obmap_patches.iat(i).data
                 )
-            )[1]
+            )[-1]
             self._df.loc[roi.Index, 'classify_by_' + name] = oc
             om[self.acc_obj_ids.data == roi.label] = oc
         self.object_class_maps[name] = InMemoryDataAccessor(om)