diff --git a/backend/api_server.py b/backend/api_server.py
index c16b406..e156806 100755
--- a/backend/api_server.py
+++ b/backend/api_server.py
@@ -18,13 +18,14 @@ from api.routers import line, stop
 
 
 @asynccontextmanager
-async def lifespan(app: FastAPI):
+async def lifespan(app: FastAPI) -> None:
     FastAPICache.init(redis_backend, prefix="api", enable=settings.cache.enable)
 
     await db.connect(settings.db, settings.clear_static_data)
     if settings.clear_static_data:
         await idfm_interface.startup()
 
+    print("OK")
     yield
 
     await db.disconnect()