diff --git a/backend/open_webui/utils/middleware.py b/backend/open_webui/utils/middleware.py
index badae9906..2c6728955 100644
--- a/backend/open_webui/utils/middleware.py
+++ b/backend/open_webui/utils/middleware.py
@@ -897,11 +897,15 @@ async def process_chat_payload(request, form_data, user, metadata, model):
     # If context is not empty, insert it into the messages
     if len(sources) > 0:
         context_string = ""
-        for source_idx, source in enumerate(sources):
+        citated_file_idx = {}
+        for _, source in enumerate(sources, 1):
             if "document" in source:
-                for doc_idx, doc_context in enumerate(source["document"]):
+                for doc_context, doc_meta in zip(source["document"], source['metadata']):
+                    file_id = doc_meta.get('file_id')
+                    if file_id not in citated_file_idx:
+                        citated_file_idx[file_id] = len(citated_file_idx) + 1
                     context_string += (
-                        f'<source id="{source_idx + 1}">{doc_context}</source>\n'
+                        f'<source id="{citated_file_idx[file_id]}">{doc_context}</source>\n'
                     )
 
         context_string = context_string.strip()