diff --git a/egs/librispeech/ASR/conformer_ctc/train.py b/egs/librispeech/ASR/conformer_ctc/train.py
index d57d693a0..ff0c8f9f4 100755
--- a/egs/librispeech/ASR/conformer_ctc/train.py
+++ b/egs/librispeech/ASR/conformer_ctc/train.py
@@ -359,7 +359,9 @@ def compute_loss(
         # Works with a phone lexicon
         decoding_graph = graph_compiler.compile(texts)
     else:
-        raise ValueError(f"Unsupported type of graph compiler: {type(graph_compiler)}")
+        raise ValueError(
+            f"Unsupported type of graph compiler: {type(graph_compiler)}"
+        )
 
     dense_fsa_vec = k2.DenseFsaVec(
         nnet_output,
@@ -386,7 +388,9 @@ def compute_loss(
             #
             # See https://github.com/k2-fsa/icefall/issues/97
             # for more details
-            unsorted_token_ids = graph_compiler.texts_to_ids(supervisions["text"])
+            unsorted_token_ids = graph_compiler.texts_to_ids(
+                supervisions["text"]
+            )
             att_loss = mmodel.decoder_forward(
                 encoder_memory,
                 memory_mask,
@@ -519,7 +523,9 @@ def train_one_epoch(
                 loss_info.write_summary(
                     tb_writer, "train/current_", params.batch_idx_train
                 )
-                tot_loss.write_summary(tb_writer, "train/tot_", params.batch_idx_train)
+                tot_loss.write_summary(
+                    tb_writer, "train/tot_", params.batch_idx_train
+                )
 
         if batch_idx > 0 and batch_idx % params.valid_interval == 0:
             logging.info("Computing validation loss")
@@ -654,7 +660,9 @@ def run(rank, world_size, args):
 
         cur_lr = optimizer._rate
         if tb_writer is not None:
-            tb_writer.add_scalar("train/learning_rate", cur_lr, params.batch_idx_train)
+            tb_writer.add_scalar(
+                "train/learning_rate", cur_lr, params.batch_idx_train
+            )
             tb_writer.add_scalar("train/epoch", epoch, params.batch_idx_train)
 
         if rank == 0:
diff --git a/icefall/graph_compiler.py b/icefall/graph_compiler.py
index e2ff03f61..570ed7d7a 100644
--- a/icefall/graph_compiler.py
+++ b/icefall/graph_compiler.py
@@ -75,7 +75,9 @@ class CtcTrainingGraphCompiler(object):
 
         # NOTE: k2.compose runs on CUDA only when treat_epsilons_specially
         # is False, so we add epsilon self-loops here
-        fsa_with_self_loops = k2.remove_epsilon_and_add_self_loops(transcript_fsa)
+        fsa_with_self_loops = k2.remove_epsilon_and_add_self_loops(
+            transcript_fsa
+        )
 
         fsa_with_self_loops = k2.arc_sort(fsa_with_self_loops)