diff --git a/egs/librispeech/ASR/conformer_ctc/subsampling.py b/egs/librispeech/ASR/conformer_ctc/subsampling.py
index b23071926..c97f1ef48 100644
--- a/egs/librispeech/ASR/conformer_ctc/subsampling.py
+++ b/egs/librispeech/ASR/conformer_ctc/subsampling.py
@@ -17,6 +17,8 @@
 
 import torch
 import torch.nn as nn
+from torch import Tensor
+from typing import Tuple
 
 
 class Conv2dSubsampling(nn.Module):