diff --git a/src/mcp/shared/session.py b/src/mcp/shared/session.py
index b617d702f..3476cbeab 100644
--- a/src/mcp/shared/session.py
+++ b/src/mcp/shared/session.py
@@ -303,7 +303,9 @@ async def send_notification(
         )
         session_message = SessionMessage(
             message=jsonrpc_notification,
-            metadata=ServerMessageMetadata(related_request_id=related_request_id) if related_request_id else None,
+            metadata=ServerMessageMetadata(related_request_id=related_request_id)
+            if related_request_id is not None
+            else None,
         )
         await self._write_stream.send(session_message)