diff --git a/egs/librispeech/ASR/pruned_transducer_stateless/pretrained.py b/egs/librispeech/ASR/pruned_transducer_stateless/pretrained.py
index b0eb4d749b..3cc4729747 100755
--- a/egs/librispeech/ASR/pruned_transducer_stateless/pretrained.py
+++ b/egs/librispeech/ASR/pruned_transducer_stateless/pretrained.py
@@ -174,6 +174,7 @@ def main():
 
     # <blk> is defined in local/train_bpe_model.py
     params.blank_id = sp.piece_to_id("<blk>")
+    params.unk_id = sp.piece_to_id("<unk>")
     params.vocab_size = sp.get_piece_size()
 
     logging.info(f"{params}")