diff --git a/packages/backend/src/core/activitypub/ApDbResolverService.ts b/packages/backend/src/core/activitypub/ApDbResolverService.ts
index 2d9e7a14e..ca148916d 100644
--- a/packages/backend/src/core/activitypub/ApDbResolverService.ts
+++ b/packages/backend/src/core/activitypub/ApDbResolverService.ts
@@ -1,5 +1,4 @@
 import { Inject, Injectable, OnApplicationShutdown } from '@nestjs/common';
-import escapeRegexp from 'escape-regexp';
 import { DI } from '@/di-symbols.js';
 import type { NotesRepository, UserPublickeysRepository, UsersRepository } from '@/models/index.js';
 import type { Config } from '@/config.js';
@@ -56,25 +55,18 @@ export class ApDbResolverService implements OnApplicationShutdown {
 
 	@bindThis
 	public parseUri(value: string | IObject): UriParseResult {
-		const uri = getApId(value);
-	
-		// the host part of a URL is case insensitive, so use the 'i' flag.
-		const localRegex = new RegExp('^' + escapeRegexp(this.config.url) + '/(\\w+)/(\\w+)(?:\/(.+))?', 'i');
-		const matchLocal = uri.match(localRegex);
-	
-		if (matchLocal) {
-			return {
-				local: true,
-				type: matchLocal[1],
-				id: matchLocal[2],
-				rest: matchLocal[3],
-			};
-		} else {
-			return {
-				local: false,
-				uri,
-			};
-		}
+		const separator = '/';
+
+		const uri = new URL(getApId(value));
+		if (uri.origin !== this.config.url) return { local: false, uri: uri.href };
+
+		const [, type, id, ...rest] = uri.pathname.split(separator);
+		return {
+			local: true,
+			type,
+			id,
+			rest: rest.length === 0 ? undefined : rest.join(separator),
+		};
 	}
 
 	/**