diff --git a/packages/reactivity/src/reactive.ts b/packages/reactivity/src/reactive.ts
index 1881955cf1c..add0765965c 100644
--- a/packages/reactivity/src/reactive.ts
+++ b/packages/reactivity/src/reactive.ts
@@ -141,7 +141,7 @@ export function shallowReactive<T extends object>(
 }
 
 type Primitive = string | number | boolean | bigint | symbol | undefined | null
-type Builtin = Primitive | Function | Date | Error | RegExp
+export type Builtin = Primitive | Function | Date | Error | RegExp
 export type DeepReadonly<T> = T extends Builtin
   ? T
   : T extends Map<infer K, infer V>
diff --git a/packages/reactivity/src/ref.ts b/packages/reactivity/src/ref.ts
index 8a48c8abcaa..701d195351f 100644
--- a/packages/reactivity/src/ref.ts
+++ b/packages/reactivity/src/ref.ts
@@ -15,7 +15,7 @@ import {
   isReadonly,
   isShallow
 } from './reactive'
-import type { ShallowReactiveMarker } from './reactive'
+import type { Builtin, ShallowReactiveMarker } from './reactive'
 import { CollectionTypes } from './collectionHandlers'
 import { createDep, Dep } from './dep'
 
@@ -138,10 +138,7 @@ class RefImpl<T> {
   public dep?: Dep = undefined
   public readonly __v_isRef = true
 
-  constructor(
-    value: T,
-    public readonly __v_isShallow: boolean
-  ) {
+  constructor(value: T, public readonly __v_isShallow: boolean) {
     this._rawValue = __v_isShallow ? value : toRaw(value)
     this._value = __v_isShallow ? value : toReactive(value)
   }
@@ -491,8 +488,7 @@ export type UnwrapRef<T> = T extends ShallowRef<infer V>
   : UnwrapRefSimple<T>
 
 export type UnwrapRefSimple<T> = T extends
-  | Function
-  | Date
+  | Builtin
   | CollectionTypes
   | BaseTypes
   | Ref