diff --git a/examples/bmn/reader.py b/examples/bmn/reader.py
index 58fd21fb0583c25a71d2c092f6bcfde7806a7a47..d8f125e10337a6e3fb9b241d4893ec96c86eba62 100644
--- a/examples/bmn/reader.py
+++ b/examples/bmn/reader.py
@@ -48,7 +48,7 @@ class BmnDataset(Dataset):
 
     def __getitem__(self, index):
         video_name = self.video_list[index]
-        video_idx = self.video_list.index(video_name)
+        video_idx = np.array(self.video_list.index(video_name)).astype('int64')
         video_feat = self.load_file(video_name)
         if self.mode == 'infer':
             return video_feat, video_idx