diff --git a/widget/src/gtk2/gtk2drawing.c b/widget/src/gtk2/gtk2drawing.c
index d43fef2be38..de68736ee22 100644
--- a/widget/src/gtk2/gtk2drawing.c
+++ b/widget/src/gtk2/gtk2drawing.c
@@ -2771,6 +2771,7 @@ moz_gtk_get_widget_border(GtkThemeWidgetType widget, gint* left, gint* top,
     case MOZ_GTK_GRIPPER:
     case MOZ_GTK_PROGRESS_CHUNK:
     case MOZ_GTK_EXPANDER:
+    case MOZ_GTK_TREEVIEW_EXPANDER:
     case MOZ_GTK_TOOLBAR_SEPARATOR:
     case MOZ_GTK_MENUSEPARATOR:
     /* These widgets have no borders.*/