diff --git a/packages/frontend/src/components/MkDialog.vue b/packages/frontend/src/components/MkDialog.vue
index fe8384a4be..6887405713 100644
--- a/packages/frontend/src/components/MkDialog.vue
+++ b/packages/frontend/src/components/MkDialog.vue
@@ -75,6 +75,8 @@ type Select = {
 	default: string | null;
 };
 
+type Result = string | number | true | null;
+
 const props = withDefaults(defineProps<{
 	type?: 'success' | 'error' | 'warning' | 'info' | 'question' | 'waiting';
 	title?: string;
@@ -101,7 +103,7 @@ const props = withDefaults(defineProps<{
 });
 
 const emit = defineEmits<{
-	(ev: 'done', v: { canceled: boolean; result: any }): void;
+	(ev: 'done', v: { canceled: true } | { canceled: false, result: Result }): void;
 	(ev: 'closed'): void;
 }>();
 
@@ -127,8 +129,11 @@ const okButtonDisabledReason = computed<null | 'charactersExceeded' | 'character
 	return null;
 });
 
-function done(canceled: boolean, result?) {
-	emit('done', { canceled, result });
+// overload function を使いたいので lint エラーを無視する
+function done(canceled: true): void;
+function done(canceled: false, result: Result): void; // eslint-disable-line no-redeclare
+function done(canceled: boolean, result?: Result): void { // eslint-disable-line no-redeclare
+	emit('done', { canceled, result } as { canceled: true } | { canceled: false, result: Result });
 	modal.value?.close();
 }
 
diff --git a/packages/frontend/src/os.ts b/packages/frontend/src/os.ts
index 3cb579f5e7..434bf8a628 100644
--- a/packages/frontend/src/os.ts
+++ b/packages/frontend/src/os.ts
@@ -279,6 +279,21 @@ export function actions<T extends {
 	});
 }
 
+// default が指定されていたら result は null になり得ないことを保証する overload function
+export function inputText(props: {
+	type?: 'text' | 'email' | 'password' | 'url';
+	title?: string;
+	text?: string;
+	placeholder?: string | null;
+	autocomplete?: string;
+	default: string;
+	minLength?: number;
+	maxLength?: number;
+}): Promise<{
+	canceled: true; result: undefined;
+} | {
+	canceled: false; result: string;
+}>;
 export function inputText(props: {
 	type?: 'text' | 'email' | 'password' | 'url';
 	title?: string;
@@ -291,7 +306,21 @@ export function inputText(props: {
 }): Promise<{
 	canceled: true; result: undefined;
 } | {
-	canceled: false; result: string;
+	canceled: false; result: string | null;
+}>;
+export function inputText(props: {
+	type?: 'text' | 'email' | 'password' | 'url';
+	title?: string;
+	text?: string;
+	placeholder?: string | null;
+	autocomplete?: string;
+	default?: string | null;
+	minLength?: number;
+	maxLength?: number;
+}): Promise<{
+	canceled: true; result: undefined;
+} | {
+	canceled: false; result: string | null;
 }> {
 	return new Promise(resolve => {
 		popup(MkDialog, {
@@ -313,6 +342,18 @@ export function inputText(props: {
 	});
 }
 
+// default が指定されていたら result は null になり得ないことを保証する overload function
+export function inputNumber(props: {
+	title?: string;
+	text?: string;
+	placeholder?: string | null;
+	autocomplete?: string;
+	default: number;
+}): Promise<{
+	canceled: true; result: undefined;
+} | {
+	canceled: false; result: number;
+}>;
 export function inputNumber(props: {
 	title?: string;
 	text?: string;
@@ -322,7 +363,18 @@ export function inputNumber(props: {
 }): Promise<{
 	canceled: true; result: undefined;
 } | {
-	canceled: false; result: number;
+	canceled: false; result: number | null;
+}>;
+export function inputNumber(props: {
+	title?: string;
+	text?: string;
+	placeholder?: string | null;
+	autocomplete?: string;
+	default?: number | null;
+}): Promise<{
+	canceled: true; result: undefined;
+} | {
+	canceled: false; result: number | null;
 }> {
 	return new Promise(resolve => {
 		popup(MkDialog, {
@@ -383,6 +435,20 @@ export function authenticateDialog(): Promise<{
 	});
 }
 
+// default が指定されていたら result は null になり得ないことを保証する overload function
+export function select<C = any>(props: {
+	title?: string;
+	text?: string;
+	default: string;
+	items: {
+		value: C;
+		text: string;
+	}[];
+}): Promise<{
+	canceled: true; result: undefined;
+} | {
+	canceled: false; result: C;
+}>;
 export function select<C = any>(props: {
 	title?: string;
 	text?: string;
@@ -394,7 +460,20 @@ export function select<C = any>(props: {
 }): Promise<{
 	canceled: true; result: undefined;
 } | {
-	canceled: false; result: C;
+	canceled: false; result: C | null;
+}>;
+export function select<C = any>(props: {
+	title?: string;
+	text?: string;
+	default?: string | null;
+	items: {
+		value: C;
+		text: string;
+	}[];
+}): Promise<{
+	canceled: true; result: undefined;
+} | {
+	canceled: false; result: C | null;
 }> {
 	return new Promise(resolve => {
 		popup(MkDialog, {
diff --git a/packages/frontend/src/pages/emoji-edit-dialog.vue b/packages/frontend/src/pages/emoji-edit-dialog.vue
index 2682c487ee..310f52f6af 100644
--- a/packages/frontend/src/pages/emoji-edit-dialog.vue
+++ b/packages/frontend/src/pages/emoji-edit-dialog.vue
@@ -135,7 +135,7 @@ async function addRole() {
 	const { canceled, result: role } = await os.select({
 		items: roles.filter(r => r.isPublic).filter(r => !currentRoleIds.includes(r.id)).map(r => ({ text: r.name, value: r })),
 	});
-	if (canceled) return;
+	if (canceled || role == null) return;
 
 	rolesThatCanBeUsedThisEmojiAsReaction.value.push(role);
 }
diff --git a/packages/frontend/src/pages/settings/preferences-backups.vue b/packages/frontend/src/pages/settings/preferences-backups.vue
index ea9c5949ab..ffa38a788a 100644
--- a/packages/frontend/src/pages/settings/preferences-backups.vue
+++ b/packages/frontend/src/pages/settings/preferences-backups.vue
@@ -203,6 +203,7 @@ async function saveNew(): Promise<void> {
 
 	const { canceled, result: name } = await os.inputText({
 		title: ts._preferencesBackups.inputName,
+		default: '',
 	});
 	if (canceled) return;
 
@@ -371,6 +372,7 @@ async function rename(id: string): Promise<void> {
 
 	const { canceled: cancel1, result: name } = await os.inputText({
 		title: ts._preferencesBackups.inputName,
+		default: '',
 	});
 	if (cancel1 || profiles.value[id].name === name) return;