diff --git a/browser/components/customizableui/CustomizableWidgets.jsm b/browser/components/customizableui/CustomizableWidgets.jsm
index 258a44f0b7f7..f1cfb6c8934b 100644
--- a/browser/components/customizableui/CustomizableWidgets.jsm
+++ b/browser/components/customizableui/CustomizableWidgets.jsm
@@ -253,7 +253,7 @@ const CustomizableWidgets = [
       let elementCount = tabsFragment.childElementCount;
       separator.hidden = !elementCount;
       while (--elementCount >= 0) {
-        tabsFragment.children[elementCount].classList.add("subviewbutton");
+        tabsFragment.children[elementCount].classList.add("subviewbutton", "cui-withicon");
       }
       recentlyClosedTabs.appendChild(tabsFragment);
 
@@ -263,7 +263,7 @@ const CustomizableWidgets = [
       elementCount = windowsFragment.childElementCount;
       separator.hidden = !elementCount;
       while (--elementCount >= 0) {
-        windowsFragment.children[elementCount].classList.add("subviewbutton");
+        windowsFragment.children[elementCount].classList.add("subviewbutton", "cui-withicon");
       }
       recentlyClosedWindows.appendChild(windowsFragment);
     },