diff --git a/packages/vue-language-core/src/generators/script.ts b/packages/vue-language-core/src/generators/script.ts
index 09ab22aa2..3a195b300 100644
--- a/packages/vue-language-core/src/generators/script.ts
+++ b/packages/vue-language-core/src/generators/script.ts
@@ -156,7 +156,7 @@ export function generate(
 			);
 		}
 		if (usedHelperTypes.ToTemplateSlots) {
-			codes.push(`type __VLS_ToTemplateSlots<T> = { [K in keyof T]: NonNullable<T[K]> extends (...args: any[]) => any ? T[K] : (props: T[K]) => any };\n`);
+			codes.push(`type __VLS_ToTemplateSlots<T> = { [K in keyof T]?: NonNullable<T[K]> extends (...args: any[]) => any ? T[K] : (props: T[K]) => any };\n`);
 		}
 		if (usedHelperTypes.PropsChildren) {
 			codes.push(`type __VLS_PropsChildren<S> = { [K in keyof (boolean extends (JSX.ElementChildrenAttribute extends never ? true : false) ? never : JSX.ElementChildrenAttribute)]?: S; };\n`);
diff --git a/packages/vue-test-workspace/vue-tsc/#2758/app.vue b/packages/vue-test-workspace/vue-tsc/#2758/app.vue
new file mode 100644
index 000000000..37e608d16
--- /dev/null
+++ b/packages/vue-test-workspace/vue-tsc/#2758/app.vue
@@ -0,0 +1,10 @@
+<script lang="ts">
+import { defineComponent } from 'vue';
+import MyComp from './main.vue';
+
+export default defineComponent({
+	components: {
+		MyComp,
+	},
+});
+</script>
diff --git a/packages/vue-test-workspace/vue-tsc/components/main.vue b/packages/vue-test-workspace/vue-tsc/components/main.vue
index 2dc1c376e..ab380a3c6 100644
--- a/packages/vue-test-workspace/vue-tsc/components/main.vue
+++ b/packages/vue-test-workspace/vue-tsc/components/main.vue
@@ -67,9 +67,9 @@ declare const ScriptSetupGenericExact: <T, >(
 	_props: NonNullable<typeof _setup>['props'] & import('vue').VNodeProps & import('vue').AllowedComponentProps & import('vue').ComponentCustomProps,
 	_ctx?: Pick<NonNullable<typeof _setup>, 'attrs' | 'emit' | 'slots'>,
 	_setup?: {
-		props: { foo: T } & { [K in keyof JSX.ElementChildrenAttribute]?: { default(data: T): any } },
+		props: { foo: T } & { [K in keyof JSX.ElementChildrenAttribute]?: { default?(data: T): any } },
 		attrs: any,
-		slots: { default(data: T): any },
+		slots: { default?(data: T): any },
 		emit: { (e: 'bar', data: T): void },
 		expose(_exposed: { baz: T }): void,
 	}
@@ -83,7 +83,7 @@ exactType(ScriptSetupGeneric, ScriptSetupGenericExact);
 exactType((new ShortDefineSlots()).$slots.foo, {} as ((props: {
 	id: string;
 } | undefined) => any) | undefined);
-exactType((new ShortDefineSlots()).$slots.bar, {} as (props: {
+exactType((new ShortDefineSlots()).$slots.bar, {} as ((props: {
 	id: number;
-}) => any);
+}) => any) | undefined);
 </script>