diff --git a/genienlp/models/general_seq2seq.py b/genienlp/models/general_seq2seq.py
index dc815557..b49e4494 100644
--- a/genienlp/models/general_seq2seq.py
+++ b/genienlp/models/general_seq2seq.py
@@ -111,7 +111,7 @@ class Seq2Seq(torch.nn.Module):
         context_rnn_state = context_rnn_state.view(batch_size, -1)
         
         if self.args.encoder_loss_type == 'mean':
-            # element-wise mean of encoder loss #https://www.aclweb.org/anthology/W18-3023.pdf
+            # element-wise mean of encoder loss https://www.aclweb.org/anthology/W18-3023.pdf
             context_value = torch.mean(context_rnn_state, dim=-1)
         elif self.args.encoder_loss_type == 'sum':
             context_value = torch.sum(context_rnn_state, dim=-1)
@@ -120,6 +120,7 @@ class Seq2Seq(torch.nn.Module):
         for i in range(0, batch_size, groups):
             indices = [j for j in range(i, i+groups)]
             groups_vals = context_value[indices]
+            assert len(groups_vals) > 1
             encoder_loss += torch.std(groups_vals).item()
             
         return encoder_loss