diff --git a/phpBB/includes/nestedset/exception.php b/phpBB/includes/nestedset/exception.php
new file mode 100644
index 0000000000..10937d0b29
--- /dev/null
+++ b/phpBB/includes/nestedset/exception.php
@@ -0,0 +1,20 @@
+<?php
+/**
+*
+* @package Nested Set
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+class phpbb_nestedset_exception extends \Exception
+{
+}
diff --git a/phpBB/includes/nestedset/forum.php b/phpBB/includes/nestedset/forum.php
new file mode 100644
index 0000000000..7ad4d2c85e
--- /dev/null
+++ b/phpBB/includes/nestedset/forum.php
@@ -0,0 +1,121 @@
+<?php
+/**
+*
+* @package Nested Set
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+class phpbb_nestedset_forum extends phpbb_nestedset_base
+{
+	/** @var phpbb_db_driver */
+	protected $db;
+
+	/** @var phpbb_lock_db */
+	protected $lock;
+
+	/** @var String */
+	protected $table_name;
+
+	/** @var String */
+	protected $item_class = 'phpbb_nestedset_item_forum';
+
+	/**
+	* Column names in the table
+	* @var array
+	*/
+	protected $table_columns = array(
+		'item_id'	=> 'forum_id',
+		'left_id'	=> 'left_id',
+		'right_id'	=> 'right_id',
+		'parent_id'	=> 'parent_id',
+		'item_parents'	=> 'forum_parents',
+	);
+
+	/**
+	* Additional SQL restrictions
+	* Allows to have multiple nestedsets in one table
+	* Columns must be prefixed with %1$s
+	* @var String
+	*/
+	protected $sql_where = '';
+
+	/**
+	* List of item properties to be cached in $item_parents
+	* @var array
+	*/
+	protected $item_basic_data = array('forum_id', 'forum_name', 'forum_type');
+
+	/**
+	* Construct
+	*
+	* @param phpbb_db_driver	$db		Database connection
+	* @param phpbb_lock_db		$lock	Lock class used to lock the table when moving forums around
+	* @param string				$table_name		Table name
+	*/
+	public function __construct(phpbb_db_driver $db, phpbb_lock_db $lock, $table_name)
+	{
+		$this->db = $db;
+		$this->lock = $lock;
+		$this->table_name = $table_name;
+	}
+
+	/**
+	* @inheritdoc
+	*/
+	public function move_children(phpbb_nestedset_item_interface $current_parent, phpbb_nestedset_item_interface $new_parent)
+	{
+		while (!$this->lock->acquire())
+		{
+			// Retry after 0.2 seconds
+			usleep(200 * 1000);
+		}
+
+		try
+		{
+			$return = parent::move_children($current_parent, $new_parent);
+		}
+		catch (phpbb_nestedset_exception $e)
+		{
+			$this->lock->release();
+			throw new phpbb_nestedset_exception('FORUM_NESTEDSET_' . $e->getMessage());
+		}
+		$this->lock->release();
+
+		return $return;
+	}
+
+	/**
+	* @inheritdoc
+	*/
+	public function set_parent(phpbb_nestedset_item_interface $item, phpbb_nestedset_item_interface $new_parent)
+	{
+		while (!$this->lock->acquire())
+		{
+			// Retry after 0.2 seconds
+			usleep(200 * 1000);
+		}
+
+		try
+		{
+			$return = parent::set_parent($item, $new_parent);
+		}
+		catch (phpbb_nestedset_exception $e)
+		{
+			$this->lock->release();
+			throw new phpbb_nestedset_exception('FORUM_NESTEDSET_' . $e->getMessage());
+		}
+		$this->lock->release();
+
+		return $return;
+	}
+}
diff --git a/phpBB/includes/nestedset/item/forum.php b/phpBB/includes/nestedset/item/forum.php
new file mode 100644
index 0000000000..9475517999
--- /dev/null
+++ b/phpBB/includes/nestedset/item/forum.php
@@ -0,0 +1,28 @@
+<?php
+/**
+*
+* @package Nested Set
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+class phpbb_nestedset_item_forum extends phpbb_nestedset_item_base
+{
+	public function __construct(array $forum_row)
+	{
+		$this->item_id = (int) $forum_row['forum_id'];
+		$this->parent_id = (int) $forum_row['parent_id'];
+		$this->left_id = (int) $forum_row['left_id'];
+		$this->right_id = (int) $forum_row['right_id'];
+		$this->item_parents_data = (string) $forum_row['forum_parents'];
+	}
+}