diff --git a/src/@types/deepcopy.d.ts b/src/@types/deepcopy.d.ts
new file mode 100644
index 0000000000..afeee51913
--- /dev/null
+++ b/src/@types/deepcopy.d.ts
@@ -0,0 +1,17 @@
+declare module 'deepcopy';
+
+declare namespace deepcopy {
+	type DeepcopyCustomizerValueType = 'Object';
+
+	type DeepcopyCustomizer<T> = (
+		value: T,
+		valueType: DeepcopyCustomizerValueType) => T;
+
+	interface DeepcopyOptions<T> {
+		customizer: DeepcopyCustomizer<T>
+	}
+
+	export function deepcopy<T>(
+		value: T,
+		options?: DeepcopyOptions<T> | DeepcopyCustomizer<T>): T;
+}
diff --git a/src/models/abuse-user-report.ts b/src/models/abuse-user-report.ts
index 1fe33f0342..f3900d348d 100644
--- a/src/models/abuse-user-report.ts
+++ b/src/models/abuse-user-report.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
 import { pack as packUser } from './user';
diff --git a/src/models/app.ts b/src/models/app.ts
index cf08ba1bda..14642e7314 100644
--- a/src/models/app.ts
+++ b/src/models/app.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import AccessToken from './access-token';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
diff --git a/src/models/auth-session.ts b/src/models/auth-session.ts
index 3458d5675f..428c707470 100644
--- a/src/models/auth-session.ts
+++ b/src/models/auth-session.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
 import { pack as packApp } from './app';
diff --git a/src/models/blocking.ts b/src/models/blocking.ts
index 4faf1a4d93..4bdaa741e9 100644
--- a/src/models/blocking.ts
+++ b/src/models/blocking.ts
@@ -1,7 +1,7 @@
 import * as mongo from 'mongodb';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import { pack as packUser, IUser } from './user';
 
 const Blocking = db.get<IBlocking>('blocking');
diff --git a/src/models/drive-file.ts b/src/models/drive-file.ts
index 24c7ac75c0..b34ba7ded8 100644
--- a/src/models/drive-file.ts
+++ b/src/models/drive-file.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import { pack as packFolder } from './drive-folder';
 import { pack as packUser } from './user';
 import monkDb, { nativeDbConn } from '../db/mongodb';
diff --git a/src/models/drive-folder.ts b/src/models/drive-folder.ts
index c95fdeb05d..b0f6e4273e 100644
--- a/src/models/drive-folder.ts
+++ b/src/models/drive-folder.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
 import DriveFile from './drive-file';
diff --git a/src/models/favorite.ts b/src/models/favorite.ts
index 20176927ae..0a8fec020f 100644
--- a/src/models/favorite.ts
+++ b/src/models/favorite.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
 import { pack as packNote } from './note';
diff --git a/src/models/follow-request.ts b/src/models/follow-request.ts
index 50235b8a9d..4f75c63a32 100644
--- a/src/models/follow-request.ts
+++ b/src/models/follow-request.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
 import { pack as packUser } from './user';
diff --git a/src/models/games/reversi/game.ts b/src/models/games/reversi/game.ts
index 3393932af8..e0d1ad1beb 100644
--- a/src/models/games/reversi/game.ts
+++ b/src/models/games/reversi/game.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../../../db/mongodb';
 import isObjectId from '../../../misc/is-objectid';
 import { IUser, pack as packUser } from '../../user';
diff --git a/src/models/games/reversi/matching.ts b/src/models/games/reversi/matching.ts
index 981665ca2c..ba2ac1bc05 100644
--- a/src/models/games/reversi/matching.ts
+++ b/src/models/games/reversi/matching.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../../../db/mongodb';
 import isObjectId from '../../../misc/is-objectid';
 import { IUser, pack as packUser } from '../../user';
diff --git a/src/models/messaging-message.ts b/src/models/messaging-message.ts
index 2c7cf37cd8..67abb4d111 100644
--- a/src/models/messaging-message.ts
+++ b/src/models/messaging-message.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import { pack as packUser } from './user';
 import { pack as packFile } from './drive-file';
 import db from '../db/mongodb';
diff --git a/src/models/mute.ts b/src/models/mute.ts
index 13cd0c6293..52775e13ca 100644
--- a/src/models/mute.ts
+++ b/src/models/mute.ts
@@ -1,7 +1,7 @@
 import * as mongo from 'mongodb';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import { pack as packUser, IUser } from './user';
 
 const Mute = db.get<IMute>('mute');
diff --git a/src/models/note-reaction.ts b/src/models/note-reaction.ts
index 256ed8203f..1152161ea5 100644
--- a/src/models/note-reaction.ts
+++ b/src/models/note-reaction.ts
@@ -1,6 +1,6 @@
 import * as mongo from 'mongodb';
 import $ from 'cafy';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
 import Reaction from './note-reaction';
diff --git a/src/models/note.ts b/src/models/note.ts
index a872eb7696..3548d1b8ec 100644
--- a/src/models/note.ts
+++ b/src/models/note.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import rap from '@prezzemolo/rap';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
diff --git a/src/models/notification.ts b/src/models/notification.ts
index 5cf1e140c8..d49494391e 100644
--- a/src/models/notification.ts
+++ b/src/models/notification.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
 import { IUser, pack as packUser } from './user';
diff --git a/src/models/signin.ts b/src/models/signin.ts
index 55485d8667..d8b05c0e30 100644
--- a/src/models/signin.ts
+++ b/src/models/signin.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 
 const Signin = db.get<ISignin>('signin');
diff --git a/src/models/user-list.ts b/src/models/user-list.ts
index ae231aff62..e7dd74bdd1 100644
--- a/src/models/user-list.ts
+++ b/src/models/user-list.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';
 
diff --git a/src/models/user.ts b/src/models/user.ts
index ef091848f9..66f515ddab 100644
--- a/src/models/user.ts
+++ b/src/models/user.ts
@@ -1,5 +1,5 @@
 import * as mongo from 'mongodb';
-const deepcopy = require('deepcopy');
+import * as deepcopy from 'deepcopy';
 import rap from '@prezzemolo/rap';
 import db from '../db/mongodb';
 import isObjectId from '../misc/is-objectid';