diff --git a/lightrag/api/lightrag_server.py b/lightrag/api/lightrag_server.py
index 5e3c9585..f7770c57 100644
--- a/lightrag/api/lightrag_server.py
+++ b/lightrag/api/lightrag_server.py
@@ -556,7 +556,7 @@ class DocumentManager:
     def __init__(
         self,
         input_dir: str,
-        supported_extensions: tuple = (".txt", ".md", ".pdf", ".docx", ".pptx", "xlsx"),
+        supported_extensions: tuple = (".txt", ".md", ".pdf", ".docx", ".pptx", ".xlsx"),
     ):
         self.input_dir = Path(input_dir)
         self.supported_extensions = supported_extensions