diff --git a/app/main.py b/app/main.py
index 288a9a4..50a48de 100644
--- a/app/main.py
+++ b/app/main.py
@@ -1,8 +1,7 @@
 from pathlib import Path
 
-from fastapi import FastAPI, Request, Response
+from fastapi import FastAPI
 from fastapi.staticfiles import StaticFiles
-from starlette.middleware.base import BaseHTTPMiddleware
 
 from app.config import UPLOAD_DIR
 from app.database import init_db
@@ -11,21 +10,20 @@ from app.routers import web, api
 app = FastAPI(title="Mailova 星笺")
 
 UPLOAD_DIR.mkdir(exist_ok=True)
+
+
+# Cache-Control for uploaded images (30 days, immutable — filenames contain UUID)
+@app.middleware("http")
+async def cache_control_middleware(request, call_next):
+    response = await call_next(request)
+    if request.url.path.startswith("/uploads/"):
+        response.headers["Cache-Control"] = "public, max-age=2592000, immutable"
+    return response
+
+
 app.mount("/static", StaticFiles(directory=str(Path(__file__).resolve().parent / "static")), name="static")
 app.mount("/uploads", StaticFiles(directory=str(UPLOAD_DIR)), name="uploads")
 
-
-# Browser cache: 30 days for uploaded images (they never change)
-class CacheControlMiddleware(BaseHTTPMiddleware):
-    async def dispatch(self, request: Request, call_next):
-        response: Response = await call_next(request)
-        if request.url.path.startswith("/uploads/"):
-            response.headers["Cache-Control"] = "public, max-age=2592000, immutable"
-        return response
-
-
-app.add_middleware(CacheControlMiddleware)
-
 app.include_router(web.router)
 app.include_router(api.router)