diff --git a/rag/nlp/search.py b/rag/nlp/search.py
index 92c6ccf27..e7b700903 100644
--- a/rag/nlp/search.py
+++ b/rag/nlp/search.py
@@ -61,7 +61,7 @@ class Dealer:
                 condition[key] = req[key]
         return condition
 
-    def search(self, req, idx_names: list[str], kb_ids: list[str], emb_mdl=None, highlight = False):
+    def search(self, req, idx_names: str | list[str], kb_ids: list[str], emb_mdl=None, highlight = False):
         filters = self.get_filters(req)
         orderBy = OrderByExpr()