diff --git a/CHANGELOG.md b/CHANGELOG.md
index f36a73395a..8ee6ba0ba1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 ChangeLog
 =========
 
+10.87.1
+----------
+* ハッシュタグ検索で大文字小文字が区別されてしまう問題を修正
+
 10.87.0
 ----------
 * ハッシュタグでユーザー検索できるように
diff --git a/src/remote/activitypub/models/person.ts b/src/remote/activitypub/models/person.ts
index 9a38bbf144..c2b99dfb04 100644
--- a/src/remote/activitypub/models/person.ts
+++ b/src/remote/activitypub/models/person.ts
@@ -143,7 +143,7 @@ export async function createPerson(uri: string, resolver?: Resolver): Promise<IU
 
 	const { fields, services } = analyzeAttachments(person.attachment);
 
-	const tags = extractHashtags(person.tag);
+	const tags = extractHashtags(person.tag).map(tag => tag.toLowerCase());
 
 	const isBot = object.type == 'Service';
 
@@ -211,7 +211,7 @@ export async function createPerson(uri: string, resolver?: Resolver): Promise<IU
 	usersChart.update(user, true);
 	//#endregion
 
-	// ハッシュタグ登録
+	// ハッシュタグ更新
 	for (const tag of tags) updateHashtag(user, tag, true, true);
 	for (const tag of (user.tags || []).filter(x => !tags.includes(x))) updateHashtag(user, tag, true, false);
 
@@ -343,7 +343,7 @@ export async function updatePerson(uri: string, resolver?: Resolver, hint?: obje
 
 	const { fields, services } = analyzeAttachments(person.attachment);
 
-	const tags = extractHashtags(person.tag);
+	const tags = extractHashtags(person.tag).map(tag => tag.toLowerCase());
 
 	const updates = {
 		lastFetchedAt: new Date(),
diff --git a/src/server/api/endpoints/i/update.ts b/src/server/api/endpoints/i/update.ts
index b3ec53223f..1de7a807c0 100644
--- a/src/server/api/endpoints/i/update.ts
+++ b/src/server/api/endpoints/i/update.ts
@@ -217,7 +217,7 @@ export default define(meta, (ps, user, app) => new Promise(async (res, rej) => {
 		if (updates.description != null) {
 			const tokens = parse(updates.description);
 			emojis = emojis.concat(extractEmojis(tokens));
-			tags = extractHashtags(tokens);
+			tags = extractHashtags(tokens).map(tag => tag.toLowerCase());
 		}
 
 		updates.emojis = emojis;
diff --git a/src/services/note/create.ts b/src/services/note/create.ts
index c94686dcc0..2a25df1553 100644
--- a/src/services/note/create.ts
+++ b/src/services/note/create.ts
@@ -234,7 +234,7 @@ export default async (user: IUser, data: Option, silent = false) => new Promise<
 		});
 	}
 
-	// ハッシュタグ登録
+	// ハッシュタグ更新
 	for (const tag of tags) updateHashtag(user, tag);
 
 	// ファイルが添付されていた場合ドライブのファイルの「このファイルが添付された投稿一覧」プロパティにこの投稿を追加