diff --git a/app/code/community/Creare/CreareSeoSitemap/Block/Sitemap.php b/app/code/community/Creare/CreareSeoSitemap/Block/Sitemap.php
index a6c6e6b..6281c23 100644
--- a/app/code/community/Creare/CreareSeoSitemap/Block/Sitemap.php
+++ b/app/code/community/Creare/CreareSeoSitemap/Block/Sitemap.php
@@ -6,6 +6,7 @@
     protected $store;
     protected $sitemapHelper;
     protected $xmlSitemaps = false;
+    protected $_flatEnabled = array();
 
     public function __construct(array $args)
     {
@@ -20,6 +21,36 @@ public function __construct(array $args)
         parent::__construct($args);
     }
 
+    /**
+     * Retrieve Catalog Product Flat Helper object
+     *
+     * @return Mage_Catalog_Helper_Product_Flat
+     */
+    public function getFlatHelper()
+    {
+        return Mage::helper('catalog/category_flat');
+    }
+
+    /**
+     * Retrieve is flat enabled flag
+     * Return always false if magento run admin
+     *
+     * @return bool
+     */
+    public function isEnabledFlat()
+    {
+        // Flat Data can be used only on frontend
+        if (Mage::app()->getStore()->isAdmin()) {
+            return false;
+        }
+        $storeId = $this->getStoreId();
+        if (!isset($this->_flatEnabled[$storeId])) {
+            $flatHelper = $this->getFlatHelper();
+            $this->_flatEnabled[$storeId] = $flatHelper->isAvailable() && $flatHelper->isBuilt($storeId);
+        }
+        return $this->_flatEnabled[$storeId];
+    }
+
     /**
      * @return Creare_CreareSeoSitemap_Helper_Data
      */
@@ -123,15 +154,24 @@ public function buildCategoryTreeHtml($parentId, $isChild = false)
     {
         if ($this->sitemapHelper->getConfig('showcategories')) {
             $categories = Mage::getModel('catalog/category')->getCollection()
-                ->addAttributeToSelect(array('url', 'name'))
+                ->addAttributeToSelect(array('name'))
                 ->addAttributeToFilter('is_active', 1)
                 ->addAttributeToFilter('parent_id', array('eq' => $parentId));
 
+            if(!$this->isEnabledFlat()) {
+                $categories->addAttributeToSelect('url');
+            }
+
             $class = ($isChild) ? "subcategories" : "top-level";
 
             $this->categoryTreeHtml .= '<ul class="' . $class . '">';
             foreach ($categories as $category) {
-                $this->categoryTreeHtml .= '<li><a href="' . $category->getUrl() . '" >' . $category->getName() . "</a>";
+                if($this->isEnabledFlat()) {
+                    $url = Mage::helper('catalog/category')->getCategoryUrl($category);
+                }else {
+                    $url = $category->getUrl();
+                }
+                $this->categoryTreeHtml .= '<li><a href="' . $url . '" >' . $category->getName() . "</a>";
                 $children = $category->getChildren();
                 if ($children) {
                     $this->categoryTreeHtml .= $this->buildCategoryTreeHtml($category->getId(), true);