diff --git a/packages/backend/src/core/MfmService.ts b/packages/backend/src/core/MfmService.ts
index 9f196d87036b..a44636f701a9 100644
--- a/packages/backend/src/core/MfmService.ts
+++ b/packages/backend/src/core/MfmService.ts
@@ -1,5 +1,5 @@
 /*
- * SPDX-FileCopyrightText: syuilo and misskey-project , Type4ny-project
+ * SPDX-FileCopyrightText: syuilo and misskey-project, Type4ny-project
  * SPDX-License-Identifier: AGPL-3.0-only
  */
 
@@ -7,19 +7,16 @@ import { URL } from 'node:url';
 import { Inject, Injectable } from '@nestjs/common';
 import * as parse5 from 'parse5';
 import { JSDOM } from 'jsdom';
-import serialize from 'w3c-xmlserializer';
 import { DI } from '@/di-symbols.js';
 import type { Config } from '@/config.js';
 import { intersperse } from '@/misc/prelude/array.js';
 import { normalizeForSearch } from '@/misc/normalize-for-search.js';
 import type { IMentionedRemoteUsers } from '@/models/Note.js';
 import { bindThis } from '@/decorators.js';
-import type { DefaultTreeAdapterMap } from 'parse5';
+import * as TreeAdapter from '../../node_modules/parse5/dist/tree-adapters/default.js';
 import type * as mfm from 'mfm-js';
 
-const treeAdapter = parse5.defaultTreeAdapter;
-type Node = DefaultTreeAdapterMap['node'];
-type ChildNode = DefaultTreeAdapterMap['childNode'];
+const treeAdapter = TreeAdapter.defaultTreeAdapter;
 
 const urlRegex = /^https?:\/\/[\w\/:%#@$&?!()\[\]~.,=+\-]+/;
 const urlRegexFull = /^https?:\/\/[\w\/:%#@$&?!()\[\]~.,=+\-]+$/;
@@ -49,7 +46,7 @@ export class MfmService {
 
 		return text.trim();
 
-		function getText(node: Node): string {
+		function getText(node: TreeAdapter.Node): string {
 			if (treeAdapter.isTextNode(node)) return node.value;
 			if (!treeAdapter.isElementNode(node)) return '';
 			if (node.nodeName === 'br') return '\n';
@@ -61,7 +58,7 @@ export class MfmService {
 			return '';
 		}
 
-		function appendChildren(childNodes: ChildNode[]): void {
+		function appendChildren(childNodes: TreeAdapter.ChildNode[]): void {
 			if (childNodes) {
 				for (const n of childNodes) {
 					analyze(n);
@@ -69,16 +66,14 @@ export class MfmService {
 			}
 		}
 
-		function analyze(node: Node) {
+		function analyze(node: TreeAdapter.Node) {
 			if (treeAdapter.isTextNode(node)) {
 				text += node.value;
 				return;
 			}
 
 			// Skip comment or document type node
-			if (!treeAdapter.isElementNode(node)) {
-				return;
-			}
+			if (!treeAdapter.isElementNode(node)) return;
 
 			switch (node.nodeName) {
 				case 'br': {
@@ -86,7 +81,8 @@ export class MfmService {
 					break;
 				}
 
-				case 'a': {
+				case 'a':
+				{
 					const txt = getText(node);
 					const rel = node.attrs.find(x => x.name === 'rel');
 					const href = node.attrs.find(x => x.name === 'href');
@@ -134,7 +130,8 @@ export class MfmService {
 					break;
 				}
 
-				case 'h1': {
+				case 'h1':
+				{
 					text += '【';
 					appendChildren(node.childNodes);
 					text += '】\n';
@@ -142,14 +139,16 @@ export class MfmService {
 				}
 
 				case 'b':
-				case 'strong': {
+				case 'strong':
+				{
 					text += '**';
 					appendChildren(node.childNodes);
 					text += '**';
 					break;
 				}
 
-				case 'small': {
+				case 'small':
+				{
 					text += '<small>';
 					appendChildren(node.childNodes);
 					text += '</small>';
@@ -157,7 +156,8 @@ export class MfmService {
 				}
 
 				case 's':
-				case 'del': {
+				case 'del':
+				{
 					text += '~~';
 					appendChildren(node.childNodes);
 					text += '~~';
@@ -165,7 +165,8 @@ export class MfmService {
 				}
 
 				case 'i':
-				case 'em': {
+				case 'em':
+				{
 					text += '<i>';
 					appendChildren(node.childNodes);
 					text += '</i>';
@@ -206,7 +207,8 @@ export class MfmService {
 				case 'h3':
 				case 'h4':
 				case 'h5':
-				case 'h6': {
+				case 'h6':
+				{
 					text += '\n\n';
 					appendChildren(node.childNodes);
 					break;
@@ -219,7 +221,8 @@ export class MfmService {
 				case 'article':
 				case 'li':
 				case 'dt':
-				case 'dd': {
+				case 'dd':
+				{
 					text += '\n';
 					appendChildren(node.childNodes);
 					break;
@@ -240,9 +243,9 @@ export class MfmService {
 			return null;
 		}
 
-		const { window } = new JSDOM() as unknown as { window: Window };
+		const fragment = JSDOM.fragment('');
 
-		const doc = window.document;
+		const doc = fragment.ownerDocument;
 
 		const body = doc.createElement('p');
 
@@ -458,6 +461,6 @@ export class MfmService {
 
 		appendChildren(nodes, body);
 
-		return serialize(body);
+		return body.outerHTML;
 	}
 }