diff --git a/egs/librispeech/ASR/prepare.sh b/egs/librispeech/ASR/prepare.sh
index 11c8e1066..59bed8389 100755
--- a/egs/librispeech/ASR/prepare.sh
+++ b/egs/librispeech/ASR/prepare.sh
@@ -302,13 +302,20 @@ fi
 if [ $stage -le 9 ] && [ $stop_stage -ge 9 ]; then
   log "Stage 9: Compile HLG"
   ./local/compile_hlg.py --lang-dir data/lang_phone
-  ./local/compile_hlg_using_openfst.py --lang-dir data/lang_phone
+
+  # Note If ./local/compile_hlg.py throws OOM,
+  # please switch to the following command
+  #
+  # ./local/compile_hlg_using_openfst.py --lang-dir data/lang_phone
 
   for vocab_size in ${vocab_sizes[@]}; do
     lang_dir=data/lang_bpe_${vocab_size}
     ./local/compile_hlg.py --lang-dir $lang_dir
 
-    ./local/compile_hlg_using_openfst.py --lang-dir $lang_dir
+    # Note If ./local/compile_hlg.py throws OOM,
+    # please switch to the following command
+    #
+    # ./local/compile_hlg_using_openfst.py --lang-dir $lang_dir
   done
 fi