diff --git a/index.js b/index.js
index 39e7fe1..c78212d 100644
--- a/index.js
+++ b/index.js
@@ -86,9 +86,11 @@ function is_nil (obj) {
  * @returns {Array<object>} filtered data
  */
 function recursive_filter (input, filters, children_key = 'children') {
-  const data = copy_object (input);
+  const data = [ ...input ];
   const filtered = [];
-  for (const e of data) {
+  for (let i = 0; i < data.length; i++) {
+    const e = { ...data[i] };
+    data[i] = e;
     let match = true;
     for (const filter of filters) {
       let search_str = '';