diff --git a/mmdet/datasets/transforms/text_transformers.py b/mmdet/datasets/transforms/text_transformers.py
index 25304d5fe45..12a0e57db3d 100644
--- a/mmdet/datasets/transforms/text_transformers.py
+++ b/mmdet/datasets/transforms/text_transformers.py
@@ -199,7 +199,7 @@ def od_aug(self, results):
 
             for i in np.random.choice(
                     valid_negative_indexes, size=num_negatives, replace=False):
-                if i not in positive_label_list:
+                if int(i) not in positive_label_list:
                     negative_label_list.add(i)
 
         random.shuffle(positive_label_list)