diff --git a/docs/2.1/_sources/notes/ddp.rst.txt b/docs/2.1/_sources/notes/ddp.rst.txt
index b1bca1a7ae1c..48cadb2218c0 100644
--- a/docs/2.1/_sources/notes/ddp.rst.txt
+++ b/docs/2.1/_sources/notes/ddp.rst.txt
@@ -28,6 +28,7 @@ updated, and all models on different processes should be exactly the same.
     import torch.multiprocessing as mp
     import torch.nn as nn
     import torch.optim as optim
+    import os
     from torch.nn.parallel import DistributedDataParallel as DDP