diff --git a/backend/open_webui/main.py b/backend/open_webui/main.py
index 202bd32c1..f13d31710 100644
--- a/backend/open_webui/main.py
+++ b/backend/open_webui/main.py
@@ -1732,8 +1732,8 @@ async def chat_completion(
         }
 
         # Check base model existence for custom models
-        if model_info_params.get("base_model_id"):
-            base_model_id = model_info_params.get("base_model_id")
+        if model_info and model_info.base_model_id:
+            base_model_id = model_info.base_model_id
             if base_model_id not in request.app.state.MODELS:
                 if ENABLE_CUSTOM_MODEL_FALLBACK:
                     default_models = (