diff --git a/egs/librispeech/ASR/pruned_transducer_stateless7/scaling.py b/egs/librispeech/ASR/pruned_transducer_stateless7/scaling.py
index 4c3271ac6..b21b531d0 100644
--- a/egs/librispeech/ASR/pruned_transducer_stateless7/scaling.py
+++ b/egs/librispeech/ASR/pruned_transducer_stateless7/scaling.py
@@ -610,7 +610,8 @@ class ConvNorm1d(torch.nn.Module):
             counts = counts.masked_fill_(src_key_padding_mask.unsqueeze(1), 0.0)
             sqnorms = sqnorms * counts
         sqnorms = self.conv(sqnorms)
-        counts = self.conv(counts)
+        # the clamping is to avoid division by zero for padding frames.
+        counts = self.conv(counts).clamp(min=0.01)
         # scales: (N, 1, T)
         scales = (sqnorms / counts  +  eps.exp()) ** -0.5
         return x * scales