diff --git a/packages/backend/src/misc/collapsed-queue.ts b/packages/backend/src/misc/collapsed-queue.ts
index 731ff58d28..1d2750b19c 100644
--- a/packages/backend/src/misc/collapsed-queue.ts
+++ b/packages/backend/src/misc/collapsed-queue.ts
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: syuilo and misskey-project
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
 export class CollapsedQueue<K, V> {
 	private jobs: Map<K, V> = new Map();