diff --git a/src/utils/vnodes.ts b/src/utils/vnodes.ts
index 27ca5f80a..516f40717 100644
--- a/src/utils/vnodes.ts
+++ b/src/utils/vnodes.ts
@@ -18,17 +18,16 @@ function flattenVNodes(vnodes: VNode[]) {
 }
 
 type VueInstance = {
-  _vnode: VNode;
   $vnode: VNode;
 };
 
 // sort children instances by vnodes order
 export function sortChildren(children: VueInstance[], parent: VueInstance) {
-  // null on SSR
-  if (!parent._vnode) {
+  const { componentOptions } = parent.$vnode;
+  if (!componentOptions || !componentOptions.children) {
     return;
   }
 
-  const vnodes = flattenVNodes(parent._vnode.children!);
+  const vnodes = flattenVNodes(componentOptions.children);
   children.sort((a, b) => vnodes.indexOf(a.$vnode) - vnodes.indexOf(b.$vnode));
 }