diff --git a/packages/backend/src/core/FetchInstanceMetadataService.ts b/packages/backend/src/core/FetchInstanceMetadataService.ts
index 9d1ce3ac5d..ad68e575cf 100644
--- a/packages/backend/src/core/FetchInstanceMetadataService.ts
+++ b/packages/backend/src/core/FetchInstanceMetadataService.ts
@@ -81,7 +81,7 @@ export class FetchInstanceMetadataService {
 			// キャッシュ有効チェックはロック取得前に行う
 			const _instance = await this.federatedInstanceService.fetch(host);
 			const now = Date.now();
-			if (_instance && _instance.infoUpdatedAt && (now - _instance.infoUpdatedAt.getTime() < REMOTE_SERVER_CACHE_TTL)) {
+			if (_instance && _instance.infoUpdatedAt != null && (now - _instance.infoUpdatedAt.getTime() < REMOTE_SERVER_CACHE_TTL)) {
 				this.logger.debug(`Skip because updated recently ${_instance.infoUpdatedAt.toJSON()}`);
 				return;
 			}
diff --git a/packages/backend/src/core/activitypub/ApRequestService.ts b/packages/backend/src/core/activitypub/ApRequestService.ts
index 8338a8ca10..631430e46a 100644
--- a/packages/backend/src/core/activitypub/ApRequestService.ts
+++ b/packages/backend/src/core/activitypub/ApRequestService.ts
@@ -91,9 +91,10 @@ export class ApRequestService {
 	@bindThis
 	public async signedPost(user: { id: MiUser['id'] }, url: string, object: unknown, level: string, digest?: string, key?: PrivateKeyWithPem): Promise<void> {
 		const body = typeof object === 'string' ? object : JSON.stringify(object);
+		const keyFetched = await this.userKeypairService.getLocalUserPrivateKey(key ?? user.id, level);
 		const req = await createSignedPost({
 			level,
-			key: await this.userKeypairService.getLocalUserPrivateKey(key ?? user.id, level),
+			key: keyFetched,
 			url,
 			body,
 			additionalHeaders: {
@@ -106,7 +107,7 @@ export class ApRequestService {
 			version: 'draft',
 			level,
 			url,
-			keyId: key.keyId,
+			keyId: keyFetched.keyId,
 		});
 
 		await this.httpRequestService.send(url, {
diff --git a/packages/backend/test/unit/FetchInstanceMetadataService.ts b/packages/backend/test/unit/FetchInstanceMetadataService.ts
index bf8f3ab0e3..f87a6765a9 100644
--- a/packages/backend/test/unit/FetchInstanceMetadataService.ts
+++ b/packages/backend/test/unit/FetchInstanceMetadataService.ts
@@ -75,62 +75,61 @@ describe('FetchInstanceMetadataService', () => {
 	test('Lock and update', async () => {
 		redisClient.set = mockRedis();
 		const now = Date.now();
-		federatedInstanceService.fetch.mockResolvedValue({ infoUpdatedAt: { getTime: () => { return now - 10 * 1000 * 60 * 60 * 24; } } } as any);
+		federatedInstanceService.fetch.mockResolvedValue({ infoUpdatedAt: new Date(now - 10 * 1000 * 60 * 60 * 24) } as any);
 		httpRequestService.getJson.mockImplementation(() => { throw Error(); });
 		const tryLockSpy = jest.spyOn(fetchInstanceMetadataService, 'tryLock');
 		const unlockSpy = jest.spyOn(fetchInstanceMetadataService, 'unlock');
 
 		await fetchInstanceMetadataService.fetchInstanceMetadata({ host: 'example.com' } as any);
+		expect(federatedInstanceService.fetch).toHaveBeenCalledTimes(1);
 		expect(tryLockSpy).toHaveBeenCalledTimes(1);
 		expect(unlockSpy).toHaveBeenCalledTimes(1);
-		expect(federatedInstanceService.fetch).toHaveBeenCalledTimes(1);
 		expect(httpRequestService.getJson).toHaveBeenCalled();
 	});
 
-	test('Lock and don\'t update', async () => {
+	test('Don\'t lock and update when recently updated', async () => {
 		redisClient.set = mockRedis();
-		const now = Date.now();
-		federatedInstanceService.fetch.mockResolvedValue({ infoUpdatedAt: { getTime: () => now } } as any);
+		federatedInstanceService.fetch.mockResolvedValue({ infoUpdatedAt: new Date() } as any);
 		httpRequestService.getJson.mockImplementation(() => { throw Error(); });
 		const tryLockSpy = jest.spyOn(fetchInstanceMetadataService, 'tryLock');
 		const unlockSpy = jest.spyOn(fetchInstanceMetadataService, 'unlock');
 
 		await fetchInstanceMetadataService.fetchInstanceMetadata({ host: 'example.com' } as any);
-		expect(tryLockSpy).toHaveBeenCalledTimes(1);
-		expect(unlockSpy).toHaveBeenCalledTimes(1);
 		expect(federatedInstanceService.fetch).toHaveBeenCalledTimes(1);
+		expect(tryLockSpy).toHaveBeenCalledTimes(0);
+		expect(unlockSpy).toHaveBeenCalledTimes(0);
 		expect(httpRequestService.getJson).toHaveBeenCalledTimes(0);
 	});
 
 	test('Do nothing when lock not acquired', async () => {
 		redisClient.set = mockRedis();
 		const now = Date.now();
-		federatedInstanceService.fetch.mockResolvedValue({ infoUpdatedAt: { getTime: () => now - 10 * 1000 * 60 * 60 * 24 } } as any);
+		federatedInstanceService.fetch.mockResolvedValue({ infoUpdatedAt: new Date(now - 10 * 1000 * 60 * 60 * 24) } as any);
 		httpRequestService.getJson.mockImplementation(() => { throw Error(); });
 		await fetchInstanceMetadataService.tryLock('example.com');
 		const tryLockSpy = jest.spyOn(fetchInstanceMetadataService, 'tryLock');
 		const unlockSpy = jest.spyOn(fetchInstanceMetadataService, 'unlock');
 
 		await fetchInstanceMetadataService.fetchInstanceMetadata({ host: 'example.com' } as any);
+		expect(federatedInstanceService.fetch).toHaveBeenCalledTimes(1);
 		expect(tryLockSpy).toHaveBeenCalledTimes(1);
 		expect(unlockSpy).toHaveBeenCalledTimes(0);
-		expect(federatedInstanceService.fetch).toHaveBeenCalledTimes(0);
 		expect(httpRequestService.getJson).toHaveBeenCalledTimes(0);
 	});
 
-	test('Do when lock not acquired but forced', async () => {
+	test('Do when forced', async () => {
 		redisClient.set = mockRedis();
 		const now = Date.now();
-		federatedInstanceService.fetch.mockResolvedValue({ infoUpdatedAt: { getTime: () => now - 10 * 1000 * 60 * 60 * 24 } } as any);
+		federatedInstanceService.fetch.mockResolvedValue({ infoUpdatedAt: new Date(now - 10 * 1000 * 60 * 60 * 24) } as any);
 		httpRequestService.getJson.mockImplementation(() => { throw Error(); });
 		await fetchInstanceMetadataService.tryLock('example.com');
 		const tryLockSpy = jest.spyOn(fetchInstanceMetadataService, 'tryLock');
 		const unlockSpy = jest.spyOn(fetchInstanceMetadataService, 'unlock');
 
 		await fetchInstanceMetadataService.fetchInstanceMetadata({ host: 'example.com' } as any, true);
+		expect(federatedInstanceService.fetch).toHaveBeenCalledTimes(0);
 		expect(tryLockSpy).toHaveBeenCalledTimes(0);
 		expect(unlockSpy).toHaveBeenCalledTimes(1);
-		expect(federatedInstanceService.fetch).toHaveBeenCalledTimes(0);
 		expect(httpRequestService.getJson).toHaveBeenCalled();
 	});
 });