diff --git a/vllm/inputs/preprocess.py b/vllm/inputs/preprocess.py
index 82ce7d392b719..87a574fb2ba62 100644
--- a/vllm/inputs/preprocess.py
+++ b/vllm/inputs/preprocess.py
@@ -160,7 +160,8 @@ def _prepare_decoder_input_ids_for_generation(
         if decoder_input_ids is None:
             # no decoder prompt input ->
             # use decoder_start_token_id as decoder_input_ids
-            decoder_input_ids = self._get_default_enc_dec_decoder_prompt()
+            # decoder_input_ids = self._get_default_enc_dec_decoder_prompt()
+            decoder_input_ids = [decoder_start_token_id]
 
         if force_bos and (len(decoder_input_ids) == 0
                           or decoder_input_ids[0] != decoder_start_token_id):