diff --git a/models/blip_nlvr.py b/models/blip_nlvr.py
index 84837167..1258e299 100644
--- a/models/blip_nlvr.py
+++ b/models/blip_nlvr.py
@@ -10,6 +10,7 @@
 import torch.nn.functional as F
 from transformers import BertTokenizer
 import numpy as np
+import os
 
 class BLIP_NLVR(nn.Module):
     def __init__(self,                 
@@ -100,4 +101,4 @@ def load_checkpoint(model,url_or_filename):
     msg = model.load_state_dict(state_dict,strict=False)
     print('load checkpoint from %s'%url_or_filename)  
     return model,msg
-            
\ No newline at end of file
+