diff --git uc_modules_add_to_cart.php uc_modules_add_to_cart.php
index f444241..bdac499 100644
--- uc_modules_add_to_cart.php
+++ uc_modules_add_to_cart.php
@@ -31,8 +31,23 @@ function uc_attribute_add_to_cart($nid, $qty, $data) {
 function uc_stock_add_to_cart($nid, $qty, $data) {
   $product = node_load($nid);
   uc_product_load($product) ;
-  $sql = "SELECT nid FROM {uc_product_stock} WHERE sku = '%s' AND nid = '%s' AND  stock <= 0";
-  $result = db_fetch_object(db_query($sql, $product->model, $nid));
+
+  if(isset($data['attributes'])) {
+    foreach ($data['attributes'] as $aid => $value) {
+	    if (is_numeric($value)) {
+	      $combination[$aid] = $value;
+	    }
+	  }
+	  ksort($combination);
+	  
+	  $result = db_query("SELECT model FROM {uc_product_adjustments} WHERE nid = %d AND combination LIKE '%s'", $nid, serialize($combination));
+	  $model = db_result($result);
+  } else {
+    $model = $product->model;
+  }
+
+  $sql = "SELECT nid FROM {uc_product_stock} WHERE sku = '%s' AND nid = '%s' AND active = 1 AND stock <= 0";
+  $result = db_fetch_object(db_query($sql, $model, $nid));
   if (  db_affected_rows($result) == 1 ) 
   {
     return array(array('success' => FALSE, 'message' => t('@product out of stock', array('@product' => $product->title )))) ;