diff --git a/src/server/api/endpoints/i/pin.ts b/src/server/api/endpoints/i/pin.ts
index ce3b0318a..d075976b7 100644
--- a/src/server/api/endpoints/i/pin.ts
+++ b/src/server/api/endpoints/i/pin.ts
@@ -1,3 +1,4 @@
+import * as mongo from 'mongodb';
 import $ from 'cafy'; import ID from '../../../../misc/cafy-id';
 import User, { ILocalUser } from '../../../../models/user';
 import Note from '../../../../models/note';
@@ -22,8 +23,8 @@ export default async (params: any, user: ILocalUser) => new Promise(async (res,
 		return rej('note not found');
 	}
 
-	let addedId;
-	let removedId;
+	let addedId: mongo.ObjectID;
+	let removedId: mongo.ObjectID;
 
 	const pinnedNoteIds = user.pinnedNoteIds || [];
 
diff --git a/src/services/i/pin.ts b/src/services/i/pin.ts
index c6d3e1178..5bf8d166b 100644
--- a/src/services/i/pin.ts
+++ b/src/services/i/pin.ts
@@ -7,7 +7,7 @@ import renderRemove from '../../remote/activitypub/renderer/remove';
 import packAp from '../../remote/activitypub/renderer';
 import { deliver } from '../../queue';
 
-export async function deliverPinnedChange(userId: mongo.ObjectID, oldId: mongo.ObjectID, newId: mongo.ObjectID) {
+export async function deliverPinnedChange(userId: mongo.ObjectID, oldId?: mongo.ObjectID, newId?: mongo.ObjectID) {
 	const user = await User.findOne({
 		_id: userId
 	});