diff --git a/framework/framework/server.ts b/framework/framework/server.ts
index 1899bc7b4..0745bb3f4 100644
--- a/framework/framework/server.ts
+++ b/framework/framework/server.ts
@@ -752,8 +752,9 @@ ${c.response.status} ${endTime - startTime}ms ${c.response.length}`);
         this.captureAllRoutes[prefix] = cb;
     }
 
-    private _applyMixin(Target: any, MixinClass: Partial<any>) {
+    private _applyMixin(Target: any, MixinClass: Partial<any> | ((t: Partial<any>) => Partial<any>)) {
         if (!('prototype' in Target)) throw new Error('Target must be a class.');
+        if (typeof MixinClass === 'function') MixinClass = MixinClass(Target.prototype);
         this.ctx.effect(() => {
             let oldValue = null;
             for (const val of Object.getOwnPropertyNames(MixinClass)) {
@@ -782,15 +783,15 @@ ${c.response.status} ${endTime - startTime}ms ${c.response.length}`);
         });
     }
 
-    public handlerMixin(MixinClass: Partial<HandlerCommon<C>>) {
+    public handlerMixin(MixinClass: Partial<HandlerCommon<C>> | ((s: HandlerCommon<C>) => Partial<HandlerCommon<C>>)) {
         return this._applyMixin(HandlerCommon, MixinClass);
     }
 
-    public httpHandlerMixin(MixinClass: Partial<Handler<C>>) {
+    public httpHandlerMixin(MixinClass: Partial<Handler<C>> | ((s: Handler<C>) => Partial<Handler<C>>)) {
         return this._applyMixin(Handler, MixinClass);
     }
 
-    public wsHandlerMixin(MixinClass: Partial<ConnectionHandler<C>>) {
+    public wsHandlerMixin(MixinClass: Partial<ConnectionHandler<C>> | ((s: ConnectionHandler<C>) => Partial<ConnectionHandler<C>>)) {
         return this._applyMixin(ConnectionHandler, MixinClass);
     }
 
diff --git a/packages/hydrooj/src/service/server.ts b/packages/hydrooj/src/service/server.ts
index 118025f3d..416fdabd1 100644
--- a/packages/hydrooj/src/service/server.ts
+++ b/packages/hydrooj/src/service/server.ts
@@ -222,15 +222,15 @@ export async function apply(ctx: Context) {
                 }
             },
         });
-        server.wsHandlerMixin({
+        server.wsHandlerMixin((s) => ({
             async onerror(err: HydroError) {
                 if (![NotFoundError, PrivilegeError, PermissionError].some((i) => err instanceof i) || this.user?._id !== 0) {
                     logger.error(`Path:${this.request.path}, User:${this.user?._id}(${this.user?.uname})`);
                     logger.error(err);
                 }
-                await super.onerror(err);
+                await s.onerror(err);
             },
-        });
+        }));
 
         on('handler/create', async (h) => {
             h.user = h.context.HydroContext.user as any;
diff --git a/packages/hydrooj/src/settings.ts b/packages/hydrooj/src/settings.ts
index 2f7194178..1435c3baa 100644
--- a/packages/hydrooj/src/settings.ts
+++ b/packages/hydrooj/src/settings.ts
@@ -74,7 +74,7 @@ export class ConfigService extends Service {
         await this.saveConfig(newConfig);
     }
 
-    requestConfig<T, S>(s: Schema<T, S>, dynamic = true): ReturnType<Schema<T, S>> {
+    requestConfig<T, S>(s: Schema<T, S>, dynamic = true): S {
         if (dynamic) {
             this.ctx.effect(() => {
                 this.settings.push(s);