diff --git a/src/utils/isPlainObject.ts b/src/utils/isPlainObject.ts
index 9d1956328a..2767112254 100644
--- a/src/utils/isPlainObject.ts
+++ b/src/utils/isPlainObject.ts
@@ -5,10 +5,6 @@
 export default function isPlainObject(obj: any): boolean {
   if (typeof obj !== 'object' || obj === null) return false
 
-  let proto = obj
-  while (Object.getPrototypeOf(proto) !== null) {
-    proto = Object.getPrototypeOf(proto)
-  }
-
-  return Object.getPrototypeOf(obj) === proto
+  const proto = obj.__proto__
+  return !proto || !Object.getPrototypeOf(proto)
 }
diff --git a/test/utils/isPlainObject.spec.ts b/test/utils/isPlainObject.spec.ts
index 62fe216152..2c984ea8ba 100644
--- a/test/utils/isPlainObject.spec.ts
+++ b/test/utils/isPlainObject.spec.ts
@@ -10,7 +10,11 @@ describe('isPlainObject', () => {
     expect(isPlainObject(new Date())).toBe(false)
     expect(isPlainObject([1, 2, 3])).toBe(false)
     expect(isPlainObject(null)).toBe(false)
+    expect(isPlainObject('')).toBe(false)
+    expect(isPlainObject(true)).toBe(false)
     expect(isPlainObject(undefined)).toBe(false)
+    expect(isPlainObject(false)).toBe(false)
     expect(isPlainObject({ x: 1, y: 2 })).toBe(true)
+    expect(isPlainObject(Object.create(null))).toBe(true)
   })
 })