diff --git a/packages/backend/src/server/api/endpoints/messaging/messages/create.ts b/packages/backend/src/server/api/endpoints/messaging/messages/create.ts
index 87f262650c..f0916b7607 100644
--- a/packages/backend/src/server/api/endpoints/messaging/messages/create.ts
+++ b/packages/backend/src/server/api/endpoints/messaging/messages/create.ts
@@ -12,18 +12,19 @@ import type { MiUserGroup } from '@/models/entities/UserGroup.js';
 import { GetterService } from '@/server/api/GetterService.js';
 import { MessagingService } from '@/core/MessagingService.js';
 import { DI } from '@/di-symbols.js';
+import { MAX_NOTE_TEXT_LENGTH } from '@/const.js';
 import { ApiError } from '../../../error.js';
 
 export const meta = {
 	tags: ['messaging'],
 
+	requireCredential: true,
+
 	limit: {
 		duration: ms('1hour'),
 		max: 120,
 	},
 
-	requireCredential: true,
-
 	kind: 'write:messaging',
 
 	res: {
@@ -82,7 +83,7 @@ export const paramDef = {
 	properties: {
 		userId: { type: 'string', format: 'misskey:id' },
 		groupId: { type: 'string', format: 'misskey:id' },
-		text: { type: 'string', nullable: true, maxLength: 3000 },
+		text: { type: 'string', maxLength: MAX_NOTE_TEXT_LENGTH, nullable: true },
 		fileId: { type: 'string', format: 'misskey:id' },
 	},
 	anyOf: [
@@ -110,8 +111,8 @@ export default class extends Endpoint<typeof meta, typeof paramDef> { // eslint-
 		private messagingService: MessagingService,
 	) {
 		super(meta, paramDef, async (ps, me) => {
-			let recipientUser: MiUser | null;
-			let recipientGroup: MiUserGroup | null;
+			let recipientUser: MiUser | undefined = undefined;
+			let recipientGroup: MiUserGroup | undefined = undefined;
 
 			if (ps.userId != null) {
 				// Myself