diff --git a/examples/librispeech/asr2/conf/transformer.yaml b/examples/librispeech/asr2/conf/transformer.yaml
index 4a50183a..3e9350ab 100644
--- a/examples/librispeech/asr2/conf/transformer.yaml
+++ b/examples/librispeech/asr2/conf/transformer.yaml
@@ -31,7 +31,7 @@ model:
     model_conf:
         ctc_weight: 0.3
         ctc_dropoutrate: 0.0
-        ctc_grad_norm_type: batch
+        ctc_grad_norm_type: null 
         lsm_weight: 0.1     # label smoothing option
         length_normalized_loss: false