diff --git a/toolkit/themes/shared/tree/tree.css b/toolkit/themes/shared/tree/tree.css
index aa4ffa899c15..54a53c36de93 100644
--- a/toolkit/themes/shared/tree/tree.css
+++ b/toolkit/themes/shared/tree/tree.css
@@ -192,6 +192,7 @@ treechildren::-moz-tree-column(insertafter) {
   fill: currentColor;
   min-width: 0;
   padding: 1px 0;
+  appearance: none;
 }
 
 .tree-columnpicker-button .button-text {