diff --git a/src/shared/util.js b/src/shared/util.js
index 709fe146..b6b3eb5d 100644
--- a/src/shared/util.js
+++ b/src/shared/util.js
@@ -56,7 +56,7 @@ export function isRegExp (v: any): boolean {
  * Check if val is a valid array index.
  */
 export function isValidArrayIndex (val: any): boolean {
-  const n = parseFloat(val)
+  const n = parseFloat(String(val))
   return n >= 0 && Math.floor(n) === n && isFinite(val)
 }