diff --git a/src/zen/common/styles/squircle-exclusions.inc.css b/src/zen/common/styles/squircle-exclusions.inc.css
index f69f6c2d5..7854bd37d 100644
--- a/src/zen/common/styles/squircle-exclusions.inc.css
+++ b/src/zen/common/styles/squircle-exclusions.inc.css
@@ -17,6 +17,7 @@
 .urlbarView-button,
 .downloadButton,
 .titlebar-button,
+.titlebar-button .toolbarbutton-icon,
 #downloads-indicator-progress-inner,
 #smartwindow-ask-button-inner,
 #PanelUI-fxa-menu-manage-account-button,