diff --git a/packages/reactivity/src/effect.ts b/packages/reactivity/src/effect.ts
index f1799a62d3a..9ef38c1b065 100644
--- a/packages/reactivity/src/effect.ts
+++ b/packages/reactivity/src/effect.ts
@@ -1,5 +1,5 @@
 import { TrackOpTypes, TriggerOpTypes } from './operations'
-import { extend, isArray, isIntegerKey, isMap, toNumber } from '@vue/shared'
+import { extend, isArray, isIntegerKey, isMap } from '@vue/shared'
 import { EffectScope, recordEffectScope } from './effectScope'
 import {
   createDep,
@@ -276,7 +276,7 @@ export function trigger(
     // trigger all effects for target
     deps = [...depsMap.values()]
   } else if (key === 'length' && isArray(target)) {
-    const newLength = toNumber(newValue)
+    const newLength = Number(newValue)
     depsMap.forEach((dep, key) => {
       if (key === 'length' || key >= newLength) {
         deps.push(dep)