diff --git a/HTML/Template/IT.php b/HTML/Template/IT.php
index 9be7015..ce72d6d 100755
--- a/HTML/Template/IT.php
+++ b/HTML/Template/IT.php
@@ -271,6 +271,13 @@ class HTML_Template_IT
      */
     var $blockinner = array();
 
+    /**
+     * Array of parent block of a block.
+     * @var      array
+     * @access   private
+     */
+    var $blockparents = array();
+
     /**
      * List of blocks to preverse even if they are "empty".
      *