diff --git a/uc_cart/uc_cart.js b/uc_cart/uc_cart.js
index f52e535..c876b39 100644
--- a/uc_cart/uc_cart.js
+++ b/uc_cart/uc_cart.js
@@ -6,9 +6,14 @@
 Drupal.behaviors.ucCart = {
   attach: function(context, settings) {
     // Add a throbber to the submit order button on the review order form.
-    jQuery('form#uc-cart-checkout-review-form input#edit-submit:not(.ucSubmitOrderThrobber-processed)', context).addClass('ucSubmitOrderThrobber-processed').click(function() {
-      jQuery(this).clone().insertAfter(this).attr('disabled', true).after('<span class="ubercart-throbber">&nbsp;&nbsp;&nbsp;&nbsp;</span>').end().hide();
-      jQuery('#uc-cart-checkout-review-form #edit-back').attr('disabled', true);
+    jQuery('form#uc-cart-checkout-review-form input#edit-submit:not(.ucSubmitOrderThrobber-processed)', context).addClass('ucSubmitOrderThrobber-processed').click(function(e) {
+      if (!jQuery('.uc-orig').length) {
+        jQuery(this).clone().attr('class', 'uc-orig').insertAfter(this).after('<span class="ubercart-throbber">&nbsp;&nbsp;&nbsp;&nbsp;</span>').end().hide();
+        jQuery('#uc-cart-checkout-review-form #edit-back')[0].disabled = true;
+        jQuery('input#edit-submit:not(.uc-orig)')[0].disabled = true;
+      } else {
+        e.preventDefault();
+      }
     });
   }
 }