diff --git a/libraries/cms/language/multilang.php b/libraries/cms/language/multilang.php
index f19b01d3cfd7a..00e00c234ac34 100644
--- a/libraries/cms/language/multilang.php
+++ b/libraries/cms/language/multilang.php
@@ -20,11 +20,13 @@ class JLanguageMultilang
 	 * Method to determine if the language filter plugin is enabled.
 	 * This works for both site and administrator.
 	 *
+	 * @param   JApplicationCms  $app  The application object
+	 *
 	 * @return  boolean  True if site is supporting multiple languages; false otherwise.
 	 *
 	 * @since   2.5.4
 	 */
-	public static function isEnabled()
+	public static function isEnabled(JApplicationCms $app = null)
 	{
 		// Flag to avoid doing multiple database queries.
 		static $tested = false;
@@ -32,8 +34,11 @@ public static function isEnabled()
 		// Status of language filter plugin.
 		static $enabled = false;
 
-		// Get application object.
-		$app = JFactory::getApplication();
+		// Get application object if not injected.
+		if (!$app)
+		{
+			$app = JFactory::getApplication();
+		}
 
 		// If being called from the front-end, we can avoid the database query.
 		if ($app->isSite())
@@ -60,6 +65,6 @@ public static function isEnabled()
 			$tested = true;
 		}
 
-		return $enabled;
+		return (bool) $enabled;
 	}
 }
diff --git a/tests/unit/suites/libraries/cms/language/JLanguageMultilangTest.php b/tests/unit/suites/libraries/cms/language/JLanguageMultilangTest.php
new file mode 100644
index 0000000000000..a00389addc79e
--- /dev/null
+++ b/tests/unit/suites/libraries/cms/language/JLanguageMultilangTest.php
@@ -0,0 +1,155 @@
+<?php
+/**
+ * @package     Joomla.UnitTest
+ * @subpackage  Language
+ *
+ * @copyright   Copyright (C) 2005 - 2015 Open Source Matters, Inc. All rights reserved.
+ * @license     GNU General Public License version 2 or later; see LICENSE
+ */
+
+use Joomla\Registry\Registry;
+
+/**
+ * Test class for JLanguageMultiLang.
+ *
+ * @package     Joomla.UnitTest
+ * @subpackage  Language
+ * @since       3.4
+ */
+class JLanguageMultiLangTest extends TestCaseDatabase
+{
+	/**
+	 * Value for test host.
+	 *
+	 * @var    string
+	 * @since  3.2
+	 */
+	const TEST_HTTP_HOST = 'mydomain.com';
+
+	/**
+	 * Value for test user agent.
+	 *
+	 * @var    string
+	 * @since  3.2
+	 */
+	const TEST_USER_AGENT = 'Mozilla/5.0';
+
+	/**
+	 * Value for test user agent.
+	 *
+	 * @var    string
+	 * @since  3.2
+	 */
+	const TEST_REQUEST_URI = '/index.php';
+
+	/**
+	 * Backup of the SERVER superglobal
+	 *
+	 * @var    array
+	 * @since  3.4
+	 */
+	protected $backupServer;
+
+	/**
+	 * Config to be injected into the Application object
+	 *
+	 * @var    Registry
+	 * @since  3.4
+	 */
+	protected $config;
+
+	/**
+	 * Setup for testing.
+	 *
+	 * @return  void
+	 *
+	 * @since   3.2
+	 */
+	public function setUp()
+	{
+		parent::setUp();
+
+		$this->saveFactoryState();
+
+		JFactory::$document = $this->getMockDocument();
+		JFactory::$language = $this->getMockLanguage();
+		JFactory::$session  = $this->getMockSession();
+
+		$this->backupServer = $_SERVER;
+
+		$_SERVER['HTTP_HOST'] = self::TEST_HTTP_HOST;
+		$_SERVER['HTTP_USER_AGENT'] = self::TEST_USER_AGENT;
+		$_SERVER['REQUEST_URI'] = self::TEST_REQUEST_URI;
+		$_SERVER['SCRIPT_NAME'] = '/index.php';
+
+		// Set the config for the app
+		$this->config = new Registry;
+		$this->config->set('session', false);
+	}
+
+	/**
+	 * Overrides the parent tearDown method.
+	 *
+	 * @return  void
+	 *
+	 * @see     PHPUnit_Framework_TestCase::tearDown()
+	 * @since   3.2
+	 */
+	protected function tearDown()
+	{
+		// Reset the dispatcher instance.
+		TestReflection::setValue('JEventDispatcher', 'instance', null);
+
+		$_SERVER = $this->backupServer;
+		$this->restoreFactoryState();
+
+		parent::tearDown();
+	}
+
+
+	/**
+	 * Gets the data set to be loaded into the database during setup
+	 *
+	 * @return  PHPUnit_Extensions_Database_DataSet_CsvDataSet
+	 *
+	 * @since   3.4
+	 */
+	protected function getDataSet()
+	{
+		$dataSet = new PHPUnit_Extensions_Database_DataSet_CsvDataSet(',', "'", '\\');
+
+		$dataSet->addTable('jos_extensions', JPATH_TEST_DATABASE . '/jos_extensions.csv');
+
+		return $dataSet;
+	}
+
+	/**
+	 * @testdox  Ensure isEnabled() proxies correctly to JApplicationSite
+	 *
+	 * @covers   JLanguageMultiLang::isEnabled
+	 * @uses     JApplicationSite
+	 */
+	public function testIsEnabledWithSiteApp()
+	{
+		$app = new JApplicationSite($this->getMockInput(), $this->config);
+
+		$this->assertFalse(
+			JLanguageMultilang::isEnabled($app)
+		);
+	}
+
+	/**
+	 * @testdox  Ensure isEnabled() database query works correctly
+	 *
+	 * @covers   JLanguageMultiLang::isEnabled
+	 * @uses     JApplicationAdministrator
+	 */
+	public function testIsEnabledWithAdminApp()
+	{
+		$app = new JApplicationAdministrator($this->getMockInput(), $this->config);
+
+		$this->assertFalse(
+			JLanguageMultilang::isEnabled($app)
+		);
+	}
+}