diff --git a/packages/frontend/src/os.ts b/packages/frontend/src/os.ts
index 7e38fe5f6d..f0af9f081b 100644
--- a/packages/frontend/src/os.ts
+++ b/packages/frontend/src/os.ts
@@ -362,7 +362,7 @@ export function select<C = any>(props: {
 	});
 }
 
-export function success() {
+export function success(): Promise<void> {
 	return new Promise((resolve, reject) => {
 		const showing = ref(true);
 		window.setTimeout(() => {
@@ -377,7 +377,7 @@ export function success() {
 	});
 }
 
-export function waiting() {
+export function waiting(): Promise<void> {
 	return new Promise((resolve, reject) => {
 		const showing = ref(true);
 		popup(MkWaitingDialog, {
@@ -528,7 +528,7 @@ export function popupMenu(items: MenuItem[] | Ref<MenuItem[]>, src?: HTMLElement
 	width?: number;
 	viaKeyboard?: boolean;
 	onClosing?: () => void;
-}) {
+}): Promise<void> {
 	return new Promise((resolve, reject) => {
 		let dispose;
 		popup(MkPopupMenu, {
@@ -551,7 +551,7 @@ export function popupMenu(items: MenuItem[] | Ref<MenuItem[]>, src?: HTMLElement
 	});
 }
 
-export function contextMenu(items: MenuItem[] | Ref<MenuItem[]>, ev: MouseEvent) {
+export function contextMenu(items: MenuItem[] | Ref<MenuItem[]>, ev: MouseEvent): Promise<void> {
 	ev.preventDefault();
 	return new Promise((resolve, reject) => {
 		let dispose;
@@ -569,7 +569,7 @@ export function contextMenu(items: MenuItem[] | Ref<MenuItem[]>, ev: MouseEvent)
 	});
 }
 
-export function post(props: Record<string, any> = {}) {
+export function post(props: Record<string, any> = {}): Promise<void> {
 	return new Promise((resolve, reject) => {
 		// NOTE: MkPostFormDialogをdynamic importするとiOSでテキストエリアに自動フォーカスできない
 		// NOTE: ただ、dynamic importしない場合、MkPostFormDialogインスタンスが使いまわされ、