diff --git a/egs/librispeech/ASR/conv_emformer_transducer_stateless/emformer.py b/egs/librispeech/ASR/conv_emformer_transducer_stateless/emformer.py
index 158b6f0fb..bfb3875ca 100644
--- a/egs/librispeech/ASR/conv_emformer_transducer_stateless/emformer.py
+++ b/egs/librispeech/ASR/conv_emformer_transducer_stateless/emformer.py
@@ -419,7 +419,8 @@ class ConvolutionModule(nn.Module):
             assert cache.shape == (B, D, self.cache_size), cache.shape
         x = torch.cat([cache, x], dim=2)  # (B, D, cache_size + U + R)
         # update cache
-        new_cache = x[:, :, -R - self.cache_size : -R]
+        x_length = x.size(2)
+        new_cache = x[:, :, x_length - R - self.cache_size : x_length - R]
 
         # 1-D depth-wise conv
         x = self.depthwise_conv(x)  # (B, D, U + R)