diff --git a/egs/librispeech/ASR/conformer_lm/train.py b/egs/librispeech/ASR/conformer_lm/train.py
index 72bc654ea..66602ea1d 100755
--- a/egs/librispeech/ASR/conformer_lm/train.py
+++ b/egs/librispeech/ASR/conformer_lm/train.py
@@ -140,7 +140,7 @@ def get_params() -> AttributeDict:
             "eos_sym": 1,
             "start_epoch": 0,
             "num_epochs": 20,
-            "num_valid_batches": 100,
+            "num_valid_batches": 200,
             "symbols_per_batch": 5000,
             "best_train_loss": float("inf"),
             "best_valid_loss": float("inf"),
@@ -288,8 +288,9 @@ def compute_loss(
 
     with torch.set_grad_enabled(is_training):
         memory, pos_emb = model(masked_src_symbols, src_key_padding_mask)
-        tgt_nll = model.decoder_nll(memory, pos_emb, src_symbols,
-                                    tgt_symbols, src_key_padding_mask)
+        decoder_nll_func = model.module.decoder_nll if isinstance(model, DDP) else model.decoder_nll
+        tgt_nll = decoder_nll_func(memory, pos_emb, src_symbols,
+                                   tgt_symbols, src_key_padding_mask)
         loss = (tgt_nll * tgt_weights).sum()
 
         assert loss.requires_grad == is_training
@@ -312,6 +313,8 @@ def compute_validation_loss(
     tot_loss = 0.0
     tot_frames = 0.0
     for batch_idx, batch in enumerate(valid_dl):
+        if batch_idx == params.num_valid_batches:
+            break
         batch = tuple(x.to(device) for x in batch)
 
         # `batch` is actually a tuple.. we'll unpack it later.
@@ -319,8 +322,6 @@ def compute_validation_loss(
         num_frames = batch[4].sum()
 
         assert loss.requires_grad is False
-        assert ctc_loss.requires_grad is False
-        assert att_loss.requires_grad is False
 
         loss_cpu = loss.detach().cpu().item()
         num_frames_cpu = num_frames.cpu().item()