diff --git uc_aac.js uc_aac.js
index bbe599e..63ce873 100644
--- uc_aac.js
+++ uc_aac.js
@@ -34,5 +34,5 @@ jQuery.fn.ucAacAttach = function() {
 }
 
 Drupal.behaviors.ucAac = function() {
-  $('.add-to-cart').ucAacAttach();
+  $('.uc-aac-cart').ucAacAttach();
 };
diff --git uc_aac.module uc_aac.module
index 0760955..2fa0b3d 100644
--- uc_aac.module
+++ uc_aac.module
@@ -35,9 +35,11 @@ function uc_aac_menu() {
  * Implementation of hook_form_alter().
  */
 function uc_aac_form_alter(&$form, $form_state, $form_id) {
-  if (strstr($form_id, 'uc_product_add_to_cart_form_')) {
+  if (strstr($form_id, 'uc_product_add_to_cart_form')) {
     static $uc_aac_js = false;
 
+    // Add a class to the cart form. This will allow us to easily identify it for binding ajax stuff.
+    $form['#attributes']['class'] .= ' uc-aac-cart';
     if (!$uc_aac_js) {
       $uc_aac_js = true;
 
@@ -52,6 +54,11 @@ function uc_aac_form_alter(&$form, $form_state, $form_id) {
       $nid = $form['nid']['#value'];
       $product =& $form['#parameters'][2];
 
+      // Add the products nid to the form, to avoid parsing formid's for an NID that may not exist.
+      $form['aac_nid'] = array(
+        '#type' => 'hidden',
+        '#value' => $nid,
+      );
       // Use qty from post or use default qty
       if (isset($_POST['qty'])) {
         $form['qty']['#default_value'] = check_plain($_POST['qty']);
@@ -150,7 +157,11 @@ function uc_aac_form_alter(&$form, $form_state, $form_id) {
  * Calculate product adjustments based on attribute option selections.
  */
 function _uc_aac_calculate() {
-  $nid = array_pop(explode('_', check_plain($_POST['form_id'])));
+  // If the nid is not set, we can't do anything.
+  if (!is_numeric($_POST['aac_nid'])) {
+    return;
+  }
+  $nid = $_POST['aac_nid'];
   $output['nid'] = $nid;
 
   // Load the node and store the submitted data for later.
@@ -225,7 +236,14 @@ function _uc_aac_calculate() {
   // Unset the form id to ensure Drupal doesn't attempt to process it.
   unset($_POST['form_id']);
   // Render the updated form
-  $output['form'] = drupal_get_form('uc_product_add_to_cart_form_'. $nid, $product);
+  // If the original form used the nid, then add it.
+  if (substr($_POST['form_id'], 'uc_product_add_to_cart_form_')) {
+    $output['form'] = drupal_get_form('uc_product_add_to_cart_form_'. $nid, $product);
+  }
+  // Otherwise use the non-standard form.
+  else {
+    $output['form'] = drupal_get_form('uc_product_add_to_cart_form', $product);
+  }
   // TODO: Fix bug where multiple add_to_cart forms on a single page have
   // elements with identical css id's after regenerating the forms