diff --git a/packages/backend/src/core/UtilityService.ts b/packages/backend/src/core/UtilityService.ts
index c84e7f212b..fca715164e 100644
--- a/packages/backend/src/core/UtilityService.ts
+++ b/packages/backend/src/core/UtilityService.ts
@@ -4,7 +4,7 @@
  */
 
 import { URL } from 'node:url';
-import { toASCII } from 'punycode';
+import punycode from 'punycode/';
 import { Inject, Injectable } from '@nestjs/common';
 import RE2 from 're2';
 import psl from 'psl';
@@ -107,13 +107,13 @@ export class UtilityService {
 
 	@bindThis
 	public toPuny(host: string): string {
-		return toASCII(host.toLowerCase());
+		return punycode.toASCII(host.toLowerCase());
 	}
 
 	@bindThis
 	public toPunyNullable(host: string | null | undefined): string | null {
 		if (host == null) return null;
-		return toASCII(host.toLowerCase());
+		return punycode.toASCII(host.toLowerCase());
 	}
 
 	@bindThis
diff --git a/packages/backend/test/unit/UtilityService.ts b/packages/backend/test/unit/UtilityService.ts
new file mode 100644
index 0000000000..b5e978569e
--- /dev/null
+++ b/packages/backend/test/unit/UtilityService.ts
@@ -0,0 +1,39 @@
+import * as assert from 'assert';
+import { Test } from '@nestjs/testing';
+
+import { CoreModule } from '@/core/CoreModule.js';
+import { UtilityService } from '@/core/UtilityService.js';
+import { GlobalModule } from '@/GlobalModule.js';
+
+describe('UtilityService', () => {
+	let utilityService: UtilityService;
+
+	beforeAll(async () => {
+		const app = await Test.createTestingModule({
+			imports: [GlobalModule, CoreModule],
+		}).compile();
+		utilityService = app.get<UtilityService>(UtilityService);
+	});
+
+	describe('punyHost', () => {
+		test('simple', () => {
+			assert.equal(utilityService.punyHost('http://www.foo.com'),'www.foo.com');
+		});
+		test('japanese', () => {
+			assert.equal(utilityService.punyHost('http://www.新聞.com'),'www.xn--efvv70d.com');
+		});
+	});
+
+	describe('punyHostPSLDomain', () => {
+		test('simple', () => {
+			assert.equal(utilityService.punyHostPSLDomain('http://www.foo.com'),'foo.com');
+		});
+		test('japanese', () => {
+			assert.equal(utilityService.punyHostPSLDomain('http://www.新聞.com'),'xn--efvv70d.com');
+		});
+		test('lower', () => {
+			assert.equal(utilityService.punyHostPSLDomain('http://foo.github.io'),'foo.github.io');
+			assert.equal(utilityService.punyHostPSLDomain('http://foo.bar.github.io'),'bar.github.io');
+		});
+	});
+});