diff --git a/phpBB/includes/acp/acp_board.php b/phpBB/includes/acp/acp_board.php
index 24b913260b..7627ff0b56 100644
--- a/phpBB/includes/acp/acp_board.php
+++ b/phpBB/includes/acp/acp_board.php
@@ -678,8 +678,12 @@ class acp_board
 		$auth_plugins = array();
 		$auth_providers = $phpbb_container->get('auth.provider_collection');
 
-		foreach($auth_providers as $key => $value)
+		foreach ($auth_providers as $key => $value)
 		{
+			if (!($value instanceof phpbb_auth_provider_interface))
+			{
+				continue;
+			}
 			$auth_plugins[] = str_replace('auth.provider.', '', $key);
 		}
 
diff --git a/phpBB/includes/auth/provider/apache.php b/phpBB/includes/auth/provider/apache.php
index 5f6f2862b6..2e80436f78 100644
--- a/phpBB/includes/auth/provider/apache.php
+++ b/phpBB/includes/auth/provider/apache.php
@@ -20,7 +20,7 @@ if (!defined('IN_PHPBB'))
  *
  * @package auth
  */
-class phpbb_auth_provider_apache implements phpbb_auth_provider_interface
+class phpbb_auth_provider_apache extends phpbb_auth_provider_base
 {
 	/**
 	 * Apache Authentication Constructor
@@ -256,20 +256,4 @@ class phpbb_auth_provider_apache implements phpbb_auth_provider_interface
 
 		return false;
 	}
-
-	/**
-	 * {@inheritdoc}
-	 */
-	public function acp($new)
-	{
-		return;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 */
-	public function logout($data, $new_session)
-	{
-		return;
-	}
 }
diff --git a/phpBB/includes/auth/provider/base.php b/phpBB/includes/auth/provider/base.php
new file mode 100644
index 0000000000..f28f352e2c
--- /dev/null
+++ b/phpBB/includes/auth/provider/base.php
@@ -0,0 +1,64 @@
+<?php
+/**
+*
+* @package auth
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+/**
+* @ignore
+*/
+if (!defined('IN_PHPBB'))
+{
+	exit;
+}
+
+/**
+* Base authentication provider class that all other providers should implement
+*
+* @package auth
+*/
+abstract class phpbb_auth_provider_base implements phpbb_auth_provider_interface
+{
+	/**
+	* {@inheritdoc}
+	*/
+	public function init()
+	{
+		return;
+	}
+
+	/**
+	* {@inheritdoc}
+	*/
+	public function autologin()
+	{
+		return;
+	}
+
+	/**
+	* {@inheritdoc}
+	*/
+	public function acp($new)
+	{
+		return;
+	}
+
+	/**
+	* {@inheritdoc}
+	*/
+	public function logout($data, $new_session)
+	{
+		return;
+	}
+
+	/**
+	* {@inheritdoc}
+	*/
+	public function validate_session($user)
+	{
+		return;
+	}
+}
diff --git a/phpBB/includes/auth/provider/db.php b/phpBB/includes/auth/provider/db.php
index 894041c9cf..0934c56d9b 100644
--- a/phpBB/includes/auth/provider/db.php
+++ b/phpBB/includes/auth/provider/db.php
@@ -22,7 +22,7 @@ if (!defined('IN_PHPBB'))
  *
  * @package auth
  */
-class phpbb_auth_provider_db implements phpbb_auth_provider_interface
+class phpbb_auth_provider_db extends phpbb_auth_provider_base
 {
 
 	/**
@@ -45,14 +45,6 @@ class phpbb_auth_provider_db implements phpbb_auth_provider_interface
 		$this->php_ext = $php_ext;
 	}
 
-	/**
-	 * {@inheritdoc}
-	 */
-	public function init()
-	{
-		return;
-	}
-
 	/**
 	 * {@inheritdoc}
 	 */
@@ -302,36 +294,4 @@ class phpbb_auth_provider_db implements phpbb_auth_provider_interface
 			'user_row'		=> $row,
 		);
 	}
-
-	/**
-	 * {@inheritdoc}
-	 */
-	public function autologin()
-	{
-		return;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 */
-	public function acp($new)
-	{
-		return;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 */
-	public function logout($data, $new_session)
-	{
-		return;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 */
-	public function validate_session($user)
-	{
-		return;
-	}
 }
diff --git a/phpBB/includes/auth/provider/ldap.php b/phpBB/includes/auth/provider/ldap.php
index f67c1e9247..e10986abf0 100644
--- a/phpBB/includes/auth/provider/ldap.php
+++ b/phpBB/includes/auth/provider/ldap.php
@@ -22,7 +22,7 @@ if (!defined('IN_PHPBB'))
  *
  * @package auth
  */
-class phpbb_auth_provider_ldap implements phpbb_auth_provider_interface
+class phpbb_auth_provider_ldap extends phpbb_auth_provider_base
 {
 	/**
 	 * LDAP Authentication Constructor
@@ -283,14 +283,6 @@ class phpbb_auth_provider_ldap implements phpbb_auth_provider_interface
 		);
 	}
 
-	/**
-	 * {@inheritdoc}
-	 */
-	public function autologin()
-	{
-		return;
-	}
-
 	/**
 	 * {@inheritdoc}
 	 */
@@ -367,20 +359,4 @@ class phpbb_auth_provider_ldap implements phpbb_auth_provider_interface
 	{
 		return str_replace(array('*', '\\', '(', ')'), array('\\*', '\\\\', '\\(', '\\)'), $string);
 	}
-
-	/**
-	 * {@inheritdoc}
-	 */
-	public function logout($data, $new_session)
-	{
-		return;
-	}
-
-	/**
-	 * {@inheritdoc}
-	 */
-	public function validate_session($user)
-	{
-		return;
-	}
 }
diff --git a/phpBB/includes/session.php b/phpBB/includes/session.php
index 66bf053f7d..e0585b1523 100644
--- a/phpBB/includes/session.php
+++ b/phpBB/includes/session.php
@@ -404,6 +404,12 @@ class phpbb_session
 					$method = basename(trim($config['auth_method']));
 
 					$provider = $phpbb_container->get('auth.provider.' . $method);
+
+					if (!($provider instanceof phpbb_auth_provider_interface))
+					{
+						throw new \RuntimeException($provider . ' must implement phpbb_auth_provider_interface');
+					}
+
 					$ret = $provider->validate_session($this->data);
 					if ($ret !== null && !$ret)
 					{
diff --git a/tests/acp_board/auth_provider/invalid.php b/tests/acp_board/auth_provider/invalid.php
new file mode 100644
index 0000000000..c12851afe6
--- /dev/null
+++ b/tests/acp_board/auth_provider/invalid.php
@@ -0,0 +1,13 @@
+<?php
+/**
+*
+* @package testing
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+class phpbb_auth_provider_acp_board_invalid
+{
+
+}
diff --git a/tests/acp_board/auth_provider/valid.php b/tests/acp_board/auth_provider/valid.php
new file mode 100644
index 0000000000..42b14cb0af
--- /dev/null
+++ b/tests/acp_board/auth_provider/valid.php
@@ -0,0 +1,16 @@
+<?php
+/**
+*
+* @package testing
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+class phpbb_auth_provider_acp_board_valid extends phpbb_auth_provider_base
+{
+	public function login($username, $password)
+	{
+		return;
+	}
+}
diff --git a/tests/acp_board/select_auth_method_test.php b/tests/acp_board/select_auth_method_test.php
new file mode 100644
index 0000000000..91aa5d1232
--- /dev/null
+++ b/tests/acp_board/select_auth_method_test.php
@@ -0,0 +1,48 @@
+<?php
+/**
+*
+* @package testing
+* @copyright (c) 2013 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+require_once dirname(__FILE__) . '/../../phpBB/includes/acp/acp_board.php';
+require_once dirname(__FILE__) . '/auth_provider/invalid.php';
+require_once dirname(__FILE__) . '/auth_provider/valid.php';
+
+class phpbb_acp_board_select_auth_method_test extends phpbb_test_case
+{
+	protected $acp_board;
+
+	public static function select_auth_method_data()
+	{
+		return array(
+			array('acp_board_valid', '<option value="acp_board_valid" selected="selected">Acp_board_valid</option>'),
+			array('acp_board_invalid', '<option value="acp_board_valid">Acp_board_valid</option>'),
+		);
+	}
+
+	public function setUp()
+	{
+		parent::setUp();
+
+		global $phpbb_container;
+		$phpbb_container = new phpbb_mock_container_builder();
+
+		$phpbb_container->set('auth.provider_collection', array(
+				'auth.provider.acp_board_valid'		=> new phpbb_auth_provider_acp_board_valid,
+				'auth.provider.acp_board_invalid'	=> new phpbb_auth_provider_acp_board_invalid,
+		));
+
+		$this->acp_board = new acp_board();
+	}
+
+	/**
+	* @dataProvider select_auth_method_data
+	*/
+	public function test_select_auth_method($selected, $expected)
+	{
+		$this->assertEquals($expected, $this->acp_board->select_auth_method($selected));
+	}
+}