diff --git a/backend/open_webui/utils/middleware.py b/backend/open_webui/utils/middleware.py
index 89fa10fbb..f2fbf4143 100644
--- a/backend/open_webui/utils/middleware.py
+++ b/backend/open_webui/utils/middleware.py
@@ -847,7 +847,7 @@ async def process_chat_payload(request, form_data, user, metadata, model):
         for source_idx, source in enumerate(sources):
             if "document" in source:
                 for doc_idx, doc_context in enumerate(source["document"]):
-                    context_string += f"<source><source_id>{source_idx}</source_id><source_context>{doc_context}</source_context></source>\n"
+                    context_string += f"<source><source_id>{source_idx + 1}</source_id><source_context>{doc_context}</source_context></source>\n"
 
         context_string = context_string.strip()
         prompt = get_last_user_message(form_data["messages"])
diff --git a/src/lib/utils/index.ts b/src/lib/utils/index.ts
index 96c8f4028..cee398139 100644
--- a/src/lib/utils/index.ts
+++ b/src/lib/utils/index.ts
@@ -64,7 +64,7 @@ export const replaceTokens = (content, sourceIds, char, user) => {
 		if (Array.isArray(sourceIds)) {
 			sourceIds.forEach((sourceId, idx) => {
 				const regex = new RegExp(`\\[${idx}\\]`, 'g');
-				segment = segment.replace(regex, `<source_id data="${idx}" title="${sourceId}" />`);
+				segment = segment.replace(regex, `<source_id data="${idx + 1}" title="${sourceId}" />`);
 			});
 		}