diff --git a/v6d3music/app.py b/v6d3music/app.py
index e13a6be..c87b7b0 100644
--- a/v6d3music/app.py
+++ b/v6d3music/app.py
@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import asyncio
 
 import aiohttp
@@ -54,7 +56,7 @@ class AppContext:
             task = asyncio.create_task(start_app(app))
             return app, task
 
-    async def __aenter__(self) -> "AppContext":
+    async def __aenter__(self) -> AppContext:
         self.__task: asyncio.Task[tuple[web.Application, asyncio.Task[None]] | None] = asyncio.create_task(self.start())
         return self
 
diff --git a/v6d3music/core/mainservice.py b/v6d3music/core/mainservice.py
index 98c078e..975178a 100644
--- a/v6d3music/core/mainservice.py
+++ b/v6d3music/core/mainservice.py
@@ -1,7 +1,9 @@
+from __future__ import annotations
+
 import asyncio
 import traceback
 from contextlib import AsyncExitStack
-from typing import AsyncIterable, Callable, TypeVar
+from typing import AsyncIterable, TypeVar
 
 import discord
 
@@ -106,7 +108,7 @@ class MainService:
     async def create(self, guild: discord.Guild) -> MainAudio:
         return await MainAudio.create(self.__servicing, self.__volumes, self.__queues, guild)
 
-    async def __aenter__(self) -> "MainService":
+    async def __aenter__(self) -> MainService:
         async with AsyncExitStack() as es:
             self.__locks = Locks()
             self.__volumes = await es.enter_async_context(DbFactory(myroot / "volume.db", kvfactory=KVJson()))
@@ -120,6 +122,7 @@ class MainService:
             self.register_instrumentation()
             self.__es = es.pop_all()
             return self
+        raise RuntimeError
 
     async def __aexit__(self, exc_type, exc_val, exc_tb):
         async with self.__es: