diff --git a/event/listener.php b/event/listener.php
index e84f55d..2560aed 100644
--- a/event/listener.php
+++ b/event/listener.php
@@ -256,7 +256,7 @@ public function build_tree_rec(&$list, $length)
 		while (current($list) !== false)
 		{
 			$next = next($list);
-			if (!($tree['forum_id'] == $next['parent_id']))
+			if (!is_array($next) || !($tree['forum_id'] == $next['parent_id']))
 			{
 				// The current node isn't our child, so we backwards and we return the current tree
 				prev($list);