diff --git a/packages/vitest/src/runtime/mocker.ts b/packages/vitest/src/runtime/mocker.ts
index 8b818bd8b399..43c0f9e1ebcc 100644
--- a/packages/vitest/src/runtime/mocker.ts
+++ b/packages/vitest/src/runtime/mocker.ts
@@ -5,7 +5,7 @@ import { isNodeBuiltin } from 'vite-node/utils'
 import { getWorkerState } from '../utils/global'
 import { getAllMockableProperties } from '../utils/base'
 import type { MockFactory, PendingSuiteMock } from '../types/mocker'
-import { spyOn } from '../integrations/spy'
+import { fn as spy } from '../integrations/spy'
 import type { VitestExecutor } from './execute'
 
 const filterPublicKeys = ['__esModule', Symbol.asyncIterator, Symbol.hasInstance, Symbol.isConcatSpreadable, Symbol.iterator, Symbol.match, Symbol.matchAll, Symbol.replace, Symbol.search, Symbol.split, Symbol.species, Symbol.toPrimitive, Symbol.toStringTag, Symbol.unscopables]
@@ -271,20 +271,9 @@ export class VitestMocker {
 
         // Sometimes this assignment fails for some unknown reason. If it does,
         // just move along.
-        if (!define(newContainer, property, isFunction ? value : {}))
+        if (!define(newContainer, property, isFunction ? spy() : {}))
           continue
 
-        if (isFunction) {
-          const mock = spyOn(newContainer, property).mockImplementation(() => undefined)
-          mock.mockRestore = () => {
-            mock.mockReset()
-            mock.mockImplementation(undefined!)
-            return mock
-          }
-          // tinyspy retains length, but jest doesn't.
-          Object.defineProperty(newContainer[property], 'length', { value: 0 })
-        }
-
         refs.track(value, newContainer[property])
         mockPropertiesOf(value, newContainer[property])
       }