diff --git a/packages/backend/src/server/api/endpoints/i/move.ts b/packages/backend/src/server/api/endpoints/i/move.ts
index 256fca2cf0..e0a9c5f9ae 100644
--- a/packages/backend/src/server/api/endpoints/i/move.ts
+++ b/packages/backend/src/server/api/endpoints/i/move.ts
@@ -9,11 +9,12 @@ import { ApiError } from '@/server/api/error.js';
 
 import { AccountMoveService } from '@/core/AccountMoveService.js';
 import { RemoteUserResolveService } from '@/core/RemoteUserResolveService.js';
-import { UserEntityService } from '@/core/entities/UserEntityService.js';
 import { ApiLoggerService } from '@/server/api/ApiLoggerService.js';
 import { GetterService } from '@/server/api/GetterService.js';
 import { ApPersonService } from '@/core/activitypub/models/ApPersonService.js';
 
+import * as Acct from '@/misc/acct.js';
+
 export const meta = {
 	tags: ['users'],
 
@@ -75,7 +76,6 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 		@Inject(DI.config)
 		private config: Config,
 
-		private userEntityService: UserEntityService,
 		private remoteUserResolveService: RemoteUserResolveService,
 		private apiLoggerService: ApiLoggerService,
 		private accountMoveService: AccountMoveService,
@@ -90,17 +90,10 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 			// abort if user has already moved
 			if (me.movedToUri) throw new ApiError(meta.errors.alreadyMoved);
 
-			let unfiltered = ps.moveToAccount;
-			if (!unfiltered) throw new ApiError(meta.errors.noSuchUser);
-
 			// parse user's input into the destination account
-			if (unfiltered.startsWith('acct:')) unfiltered = unfiltered.substring(5);
-			if (unfiltered.startsWith('@')) unfiltered = unfiltered.substring(1);
-			if (!unfiltered.includes('@')) throw new ApiError(meta.errors.noSuchUser);
-
-			const userAddress = unfiltered.split('@');
+			const { username, host } = Acct.parse(ps.moveToAccount);
 			// retrieve the destination account
-			let moveTo = await this.remoteUserResolveService.resolveUser(userAddress[0], userAddress[1]).catch((e) => {
+			let moveTo = await this.remoteUserResolveService.resolveUser(username, host).catch((e) => {
 				this.apiLoggerService.logger.warn(`failed to resolve remote user: ${e}`);
 				throw new ApiError(meta.errors.noSuchUser);
 			});
diff --git a/packages/backend/src/server/api/endpoints/i/update.ts b/packages/backend/src/server/api/endpoints/i/update.ts
index 5971791874..a0ed7595d5 100644
--- a/packages/backend/src/server/api/endpoints/i/update.ts
+++ b/packages/backend/src/server/api/endpoints/i/update.ts
@@ -3,6 +3,7 @@ import * as mfm from 'mfm-js';
 import { Inject, Injectable } from '@nestjs/common';
 import { extractCustomEmojisFromMfm } from '@/misc/extract-custom-emojis-from-mfm.js';
 import { extractHashtags } from '@/misc/extract-hashtags.js';
+import * as Acct from '@/misc/acct.js';
 import type { UsersRepository, DriveFilesRepository, UserProfilesRepository, PagesRepository } from '@/models/index.js';
 import type { User } from '@/models/entities/User.js';
 import { birthdaySchema, descriptionSchema, locationSchema, nameSchema } from '@/models/entities/User.js';
@@ -303,14 +304,11 @@ export default class extends Endpoint<typeof meta, typeof paramDef> {
 				// Parse user's input into the old account
 				const newAlsoKnownAs = new Set<string>();
 				for (const line of ps.alsoKnownAs) {
-					let unfiltered = line;
-					if (unfiltered.startsWith('acct:')) unfiltered = unfiltered.substring(5);
-					if (unfiltered.startsWith('@')) unfiltered = unfiltered.substring(1);
-					if (!unfiltered.includes('@')) throw new ApiError(meta.errors.noSuchUser);
+					if (!line) throw new ApiError(meta.errors.noSuchUser);
+					const { username, host } = Acct.parse(line);
 
-					const userAddress = unfiltered.split('@');
 					// Retrieve the old account
-					const knownAs = await this.remoteUserResolveService.resolveUser(userAddress[0], userAddress[1]).catch((e) => {
+					const knownAs = await this.remoteUserResolveService.resolveUser(username, host).catch((e) => {
 						this.apiLoggerService.logger.warn(`failed to resolve dstination user: ${e}`);
 						throw new ApiError(meta.errors.noSuchUser);
 					});
diff --git a/packages/backend/test/e2e/move.ts b/packages/backend/test/e2e/move.ts
index 5c6e5937a1..3dd0303fb8 100644
--- a/packages/backend/test/e2e/move.ts
+++ b/packages/backend/test/e2e/move.ts
@@ -57,6 +57,26 @@ describe('Account Move', () => {
 			assert.strictEqual(newBob.alsoKnownAs[0], `${url.origin}/users/${alice.id}`);
 		});
 
+		test('Able to create a local alias without hostname', async () => {
+			await api('/i/update', {
+				alsoKnownAs: ['@alice'],
+			}, bob);
+
+			const newBob = await Users.findOneByOrFail({ id: bob.id });
+			assert.strictEqual(newBob.alsoKnownAs?.length, 1);
+			assert.strictEqual(newBob.alsoKnownAs[0], `${url.origin}/users/${alice.id}`);
+		});
+
+		test('Able to create a local alias without @', async () => {
+			await api('/i/update', {
+				alsoKnownAs: ['alice'],
+			}, bob);
+
+			const newBob = await Users.findOneByOrFail({ id: bob.id });
+			assert.strictEqual(newBob.alsoKnownAs?.length, 1);
+			assert.strictEqual(newBob.alsoKnownAs[0], `${url.origin}/users/${alice.id}`);
+		});
+
 		test('Able to set remote user (but may fail)', async () => {
 			const res = await api('/i/update', {
 				alsoKnownAs: ['@syuilo@example.com'],
@@ -88,13 +108,21 @@ describe('Account Move', () => {
 		});
 
 		test('Unable to add a nonexisting local account to alsoKnownAs', async () => {
-			const res = await api('/i/update', {
+			const res1 = await api('/i/update', {
 				alsoKnownAs: [`@nonexist@${url.hostname}`],
 			}, bob);
 
-			assert.strictEqual(res.status, 400);
-			assert.strictEqual(res.body.error.code, 'NO_SUCH_USER');
-			assert.strictEqual(res.body.error.id, 'fcd2eef9-a9b2-4c4f-8624-038099e90aa5');
+			assert.strictEqual(res1.status, 400);
+			assert.strictEqual(res1.body.error.code, 'NO_SUCH_USER');
+			assert.strictEqual(res1.body.error.id, 'fcd2eef9-a9b2-4c4f-8624-038099e90aa5');
+
+			const res2 = await api('/i/update', {
+				alsoKnownAs: ['@alice', 'nonexist'],
+			}, bob);
+
+			assert.strictEqual(res2.status, 400);
+			assert.strictEqual(res2.body.error.code, 'NO_SUCH_USER');
+			assert.strictEqual(res2.body.error.id, 'fcd2eef9-a9b2-4c4f-8624-038099e90aa5');
 		});
 
 		test('Able to add two existing local account to alsoKnownAs', async () => {
@@ -121,24 +149,6 @@ describe('Account Move', () => {
 			assert.strictEqual(newBob.alsoKnownAs[0], `${url.origin}/users/${carol.id}`);
 			assert.strictEqual(newBob.alsoKnownAs[1], `${url.origin}/users/${dave.id}`);
 		});
-
-		test('Unable to create an alias without the second @', async () => {
-			const res1 = await api('/i/update', {
-				alsoKnownAs: ['@alice'],
-			}, bob);
-
-			assert.strictEqual(res1.status, 400);
-			assert.strictEqual(res1.body.error.code, 'NO_SUCH_USER');
-			assert.strictEqual(res1.body.error.id, 'fcd2eef9-a9b2-4c4f-8624-038099e90aa5');
-
-			const res2 = await api('/i/update', {
-				alsoKnownAs: ['alice'],
-			}, bob);
-
-			assert.strictEqual(res2.status, 400);
-			assert.strictEqual(res2.body.error.code, 'NO_SUCH_USER');
-			assert.strictEqual(res2.body.error.id, 'fcd2eef9-a9b2-4c4f-8624-038099e90aa5');
-		});
 	});
 
 	describe('Local to Local', () => {