diff --git a/egs/librispeech/ASR/pruned_transducer_stateless7_ctc_bs/frame_reducer.py b/egs/librispeech/ASR/pruned_transducer_stateless7_ctc_bs/frame_reducer.py
index 4a19edf66..bc3fc57eb 100644
--- a/egs/librispeech/ASR/pruned_transducer_stateless7_ctc_bs/frame_reducer.py
+++ b/egs/librispeech/ASR/pruned_transducer_stateless7_ctc_bs/frame_reducer.py
@@ -44,6 +44,7 @@ class FrameReducer(nn.Module):
         x: torch.Tensor,
         x_lens: torch.Tensor,
         ctc_output: torch.Tensor,
+        blank_id: int = 0,
     ) -> Tuple[torch.Tensor, torch.Tensor]:
         """
         Args:
@@ -54,6 +55,8 @@ class FrameReducer(nn.Module):
               `x` before padding.
             ctc_output:
               The CTC output with shape [N, T, vocab_size].
+            blank_id:
+              The blank id of ctc_output.
         Returns:
             out:
               The frame reduced encoder output with shape [N, T', C].
@@ -65,7 +68,7 @@ class FrameReducer(nn.Module):
         N, T, C = x.size()
 
         padding_mask = make_pad_mask(x_lens)
-        non_blank_mask = (ctc_output[:, :, 0] < math.log(0.9)) * (~padding_mask)
+        non_blank_mask = (ctc_output[:, :, blank_id] < math.log(0.9)) * (~padding_mask)
 
         out_lens = non_blank_mask.sum(dim=1)
         max_len = out_lens.max()