diff --git a/xtuner/dataset/map_fns/dataset_map_fns/openai_map_fn.py b/xtuner/dataset/map_fns/dataset_map_fns/openai_map_fn.py
index c1798dc45..468e738f7 100644
--- a/xtuner/dataset/map_fns/dataset_map_fns/openai_map_fn.py
+++ b/xtuner/dataset/map_fns/dataset_map_fns/openai_map_fn.py
@@ -32,7 +32,8 @@ def openai_map_fn(example):
         elif msg['role'] == 'user':
             input += msg['content']
         elif msg['role'] == 'assistant':
-            output_with_loss = msg.get('loss', True)
+            output_with_loss = msg.get('loss', 'True')
+            output_with_loss = str(output_with_loss)
             output_with_loss = output_with_loss.lower() == 'true'
             conversation.append({
                 'system': system,