diff --git a/corrlib/tracker.py b/corrlib/tracker.py
index f513b56..e6e9c04 100644
--- a/corrlib/tracker.py
+++ b/corrlib/tracker.py
@@ -1,6 +1,7 @@
 import os
 from configparser import ConfigParser
 from .trackers import datalad as dl
+from typing import Optional
 
 
 def get_tracker(path: str) -> str:
@@ -21,7 +22,7 @@ def get(path: str, file: str) -> None:
     return
 
 
-def save(path: str, message: str, files: list[str]) -> None:
+def save(path: str, message: str, files: Optional[list[str]]=None) -> None:
     tracker = get_tracker(path)
     if tracker == 'datalad':
         dl.save(path, message, files)