diff --git a/packages/backend/src/misc/renote.ts b/packages/backend/src/misc/renote.ts
index 015c26d65..758dcdd05 100644
--- a/packages/backend/src/misc/renote.ts
+++ b/packages/backend/src/misc/renote.ts
@@ -1,5 +1,5 @@
 import { Note } from '@/models/entities/note.js';
 
-export function isPureRenote(note: Note): boolean {
+export function isPureRenote(note: Note): note is Note & { renoteId: string, text: null, fileIds: null | never[], hasPoll: false } {
 	return note.renoteId != null && note.text == null && (note.fileIds == null || note.fileIds.length === 0) && !note.hasPoll;
 }