diff --git a/sao/src/view/tree.js b/sao/src/view/tree.js
index 8e6e64ccf8..78aecf2a76 100644
--- a/sao/src/view/tree.js
+++ b/sao/src/view/tree.js
@@ -1027,9 +1027,9 @@
                 var selector = `tr > td:nth-child(${i + offset + 1})`;
                 if ((thead_visible && column.header.is(':hidden')) ||
                     (column.header.css('display') == 'none')) {
-                    to_hide.add(this.tbody.find(selector));
+                    to_hide = to_hide.add(this.tbody.find(selector));
                 } else {
-                    to_show.add(this.tbody.find(selector));
+                    to_show = to_show.add(this.tbody.find(selector));
                 }
             }