diff --git a/python/cocoindex/lib.py b/python/cocoindex/lib.py
index 2d77e3940..2e4b009f7 100644
--- a/python/cocoindex/lib.py
+++ b/python/cocoindex/lib.py
@@ -12,7 +12,7 @@
 from .convert import dump_engine_object
 
 
-def init(settings: setting.Settings | None):
+def init(settings: setting.Settings | None = None):
     """
     Initialize the cocoindex library.