diff --git a/packages/dts-test/setupHelpers.test-d.ts b/packages/dts-test/setupHelpers.test-d.ts
index 883ebe6b254..8b6a53a8183 100644
--- a/packages/dts-test/setupHelpers.test-d.ts
+++ b/packages/dts-test/setupHelpers.test-d.ts
@@ -19,6 +19,7 @@ describe('defineProps w/ type declaration', () => {
   // type declaration
   const props = defineProps<{
     foo: string
+    baz?: number
     bool?: boolean
     boolAndUndefined: boolean | undefined
     file?: File | File[]
@@ -28,6 +29,12 @@ describe('defineProps w/ type declaration', () => {
   // @ts-expect-error
   props.bar
 
+  expectType<{
+    foo: string
+    baz: number | undefined
+    bool: boolean
+    boolAndUndefined: boolean
+  }>(props)
   expectType<boolean>(props.bool)
   expectType<boolean>(props.boolAndUndefined)
 })
diff --git a/packages/runtime-core/src/apiSetupHelpers.ts b/packages/runtime-core/src/apiSetupHelpers.ts
index 39d8edbcc20..7e16c0f99de 100644
--- a/packages/runtime-core/src/apiSetupHelpers.ts
+++ b/packages/runtime-core/src/apiSetupHelpers.ts
@@ -92,7 +92,9 @@ export function defineProps() {
   return null as any
 }
 
-export type DefineProps<T, BKeys extends keyof T> = Readonly<T> & {
+export type DefineProps<T, BKeys extends keyof T> = Readonly<
+  LooseRequired<T>
+> & {
   readonly [K in BKeys]-?: boolean
 }