diff --git a/api/core/rag/splitter/fixed_text_splitter.py b/api/core/rag/splitter/fixed_text_splitter.py
index 9ee9f1fd59..bcaf299892 100644
--- a/api/core/rag/splitter/fixed_text_splitter.py
+++ b/api/core/rag/splitter/fixed_text_splitter.py
@@ -102,7 +102,7 @@ class FixedRecursiveCharacterTextSplitter(EnhanceRecursiveCharacterTextSplitter)
                 splits = text.split()
             else:
                 splits = text.split(separator)
-                splits = [item + separator if i < len(splits) else item for i, item in splits]
+                splits = [item + separator if i < len(splits) else item for i, item in enumerate(splits)]
         else:
             splits = list(text)
         splits = [s for s in splits if (s not in {"", "\n"})]