diff --git a/packages/jupyter-ai/jupyter_ai/chat_handlers/learn.py b/packages/jupyter-ai/jupyter_ai/chat_handlers/learn.py
index 89770f0d2..2bd1d6002 100644
--- a/packages/jupyter-ai/jupyter_ai/chat_handlers/learn.py
+++ b/packages/jupyter-ai/jupyter_ai/chat_handlers/learn.py
@@ -175,7 +175,7 @@ def _build_list_response(self):
         return message
 
     async def learn_dir(
-        self, path: str, chunk_size: int, chunk_overlap: int, all_files: bool
+        self, path: str, chunk_size: int, chunk_overlap: int, all_files: bool=False
     ):
         dask_client: DaskClient = await self.dask_client_future
         splitter_kwargs = {"chunk_size": chunk_size, "chunk_overlap": chunk_overlap}