diff --git a/packages/backend/migration/1662943835603-larger-follow-request-ids.js b/packages/backend/migration/1662943835603-larger-follow-request-ids.js
new file mode 100644
index 000000000..f13401d51
--- /dev/null
+++ b/packages/backend/migration/1662943835603-larger-follow-request-ids.js
@@ -0,0 +1,12 @@
+export class largerFollowRequestIds1662943835603 {
+	name = 'largerFollowRequestIds1662943835603';
+
+	async up(queryRunner) {
+		await queryRunner.query(`ALTER TABLE "follow_request" ALTER COLUMN "requestId" TYPE VARCHAR(2048)`);
+	}
+
+	async down(queryRunner) {
+		await queryRunner.query(`ALTER TABLE "follow_request" ALTER COLUMN "requestId" TYPE VARCHAR(128)`);
+	}
+
+}
diff --git a/packages/backend/src/models/entities/follow-request.ts b/packages/backend/src/models/entities/follow-request.ts
index 3a2e48ce9..cd0acc453 100644
--- a/packages/backend/src/models/entities/follow-request.ts
+++ b/packages/backend/src/models/entities/follow-request.ts
@@ -40,7 +40,7 @@ export class FollowRequest {
 	public follower: User | null;
 
 	@Column('varchar', {
-		length: 128, nullable: true,
+		length: 2048, nullable: true,
 		comment: 'id of Follow Activity.',
 	})
 	public requestId: string | null;
diff --git a/packages/backend/src/queue/processors/inbox.ts b/packages/backend/src/queue/processors/inbox.ts
index bf25aca20..167e5bc6b 100644
--- a/packages/backend/src/queue/processors/inbox.ts
+++ b/packages/backend/src/queue/processors/inbox.ts
@@ -127,13 +127,18 @@ export default async (job: Bull.Job<InboxJobData>): Promise<string> => {
 		}
 	}
 
-	// activity.idがあればホストが署名者のホストであることを確認する
 	if (typeof activity.id === 'string') {
+		// Verify that activity and actor are from the same host.
 		const signerHost = extractDbHost(authUser.user.uri!);
 		const activityIdHost = extractDbHost(activity.id);
 		if (signerHost !== activityIdHost) {
 			return `skip: signerHost(${signerHost}) !== activity.id host(${activityIdHost}`;
 		}
+
+		// Verify that the id has a sane length
+		if (activity.id.length > 2048) {
+			return `skip: overly long id from ${signerHost}`;
+		}
 	}
 
 	// Update stats