diff --git a/homeassistant/components/synology_dsm/config_flow.py b/homeassistant/components/synology_dsm/config_flow.py
index 89bbc4ae8c2..0314165eb41 100644
--- a/homeassistant/components/synology_dsm/config_flow.py
+++ b/homeassistant/components/synology_dsm/config_flow.py
@@ -383,7 +383,7 @@ class SynologyDSMOptionsFlowHandler(OptionsFlow):
         return self.async_show_form(step_id="init", data_schema=data_schema)
 
 
-def _login_and_fetch_syno_info(api: SynologyDSM, otp_code: str) -> str:
+def _login_and_fetch_syno_info(api: SynologyDSM, otp_code: str | None) -> str:
     """Login to the NAS and fetch basic data."""
     # These do i/o
     api.login(otp_code)