diff --git a/packages/backend/src/models/repositories/drive-file.ts b/packages/backend/src/models/repositories/drive-file.ts
index c15f5b605..b626359d9 100644
--- a/packages/backend/src/models/repositories/drive-file.ts
+++ b/packages/backend/src/models/repositories/drive-file.ts
@@ -29,7 +29,7 @@ export const DriveFileRepository = db.getRepository(DriveFile).extend({
 
 	getPublicProperties(file: DriveFile): DriveFile['properties'] {
 		if (file.properties.orientation != null) {
-			const properties = JSON.parse(JSON.stringify(file.properties));
+			const properties = structuredClone(file.properties);
 			if (file.properties.orientation >= 5) {
 				[properties.width, properties.height] = [properties.height, properties.width];
 			}
diff --git a/packages/backend/src/server/web/manifest.ts b/packages/backend/src/server/web/manifest.ts
index bcbf9b76a..61d766006 100644
--- a/packages/backend/src/server/web/manifest.ts
+++ b/packages/backend/src/server/web/manifest.ts
@@ -1,16 +1,16 @@
 import Koa from 'koa';
-import manifest from './manifest.json' assert { type: 'json' };
 import { fetchMeta } from '@/misc/fetch-meta.js';
+import manifest from './manifest.json' assert { type: 'json' };
 
 export const manifestHandler = async (ctx: Koa.Context) => {
-	const json = JSON.parse(JSON.stringify(manifest));
+	const res = structuredClone(manifest);
 
 	const instance = await fetchMeta(true);
 
-	json.short_name = instance.name || 'Misskey';
-	json.name = instance.name || 'Misskey';
-	if (instance.themeColor) json.theme_color = instance.themeColor;
+	res.short_name = instance.name || 'Misskey';
+	res.name = instance.name || 'Misskey';
+	if (instance.themeColor) res.theme_color = instance.themeColor;
 
 	ctx.set('Cache-Control', 'max-age=300');
-	ctx.body = json;
+	ctx.body = res;
 };
diff --git a/packages/backend/src/services/relay.ts b/packages/backend/src/services/relay.ts
index 1ab45588d..08bf72cc2 100644
--- a/packages/backend/src/services/relay.ts
+++ b/packages/backend/src/services/relay.ts
@@ -88,7 +88,7 @@ export async function deliverToRelays(user: { id: User['id']; host: null; }, act
 	}));
 	if (relays.length === 0) return;
 
-	const copy = JSON.parse(JSON.stringify(activity));
+	const copy = structuredClone(activity);
 	if (!copy.to) copy.to = ['https://www.w3.org/ns/activitystreams#Public'];
 
 	const signed = await attachLdSignature(copy, user);