diff --git a/js/commerce_add_to_cart_confirmation.js b/js/commerce_add_to_cart_confirmation.js
index e165bab..4a783dc 100644
--- a/js/commerce_add_to_cart_confirmation.js
+++ b/js/commerce_add_to_cart_confirmation.js
@@ -22,7 +22,7 @@
 
       if ($(overlayContentSelector).length > 0) {
         // Add the background overlay.
-        $(overlayParentSelector).append('<div class="' + overlayClass + '"></div>');
+        $(overlayParentSelector).once().append('<div class="' + overlayClass + '"></div>');
 
         // Enable the close link.
         $('.commerce-add-to-cart-confirmation-close').bind('click touchend', function(e) {