diff --git a/rag/raptor.py b/rag/raptor.py
index fcc686565..6a6013605 100644
--- a/rag/raptor.py
+++ b/rag/raptor.py
@@ -46,7 +46,7 @@ class RecursiveAbstractiveProcessing4TreeOrganizedRetrieval:
 
     def _embedding_encode(self, txt):
         response = get_embed_cache(self._embd_model.llm_name, txt)
-        if response:
+        if response is not None:
             return response
         embds, _ = self._embd_model.encode([txt])
         if len(embds) < 1 or len(embds[0]) < 1: