diff --git a/lib/private/l10n.php b/lib/private/l10n.php
index 085914a68b..43e1121b98 100644
--- a/lib/private/l10n.php
+++ b/lib/private/l10n.php
@@ -88,44 +88,6 @@ class OC_L10N implements \OCP\IL10N {
 		$this->lang = $lang;
 	}
 
-	/**
-	 * @return string
-	 */
-	public static function setLanguageFromRequest() {
-		if (isset($_SERVER['HTTP_ACCEPT_LANGUAGE'])) {
-			$available = self::findAvailableLanguages();
-
-			// E.g. make sure that 'de' is before 'de_DE'.
-			sort($available);
-
-			$preferences = preg_split('/,\s*/', strtolower($_SERVER['HTTP_ACCEPT_LANGUAGE']));
-			foreach ($preferences as $preference) {
-				list($preferred_language) = explode(';', $preference);
-				$preferred_language = str_replace('-', '_', $preferred_language);
-				foreach ($available as $available_language) {
-					if ($preferred_language === strtolower($available_language)) {
-						if (!self::$language) {
-							self::$language = $available_language;
-						}
-						return $available_language;
-					}
-				}
-				foreach ($available as $available_language) {
-					if (substr($preferred_language, 0, 2) === $available_language) {
-						if (!self::$language) {
-							self::$language = $available_language;
-						}
-						return $available_language;
-					}
-				}
-			}
-		}
-
-		self::$language = 'en';
-		// Last try: English
-		return 'en';
-	}
-
 	/**
 	 * @param $transFile
 	 * @param bool $mergeTranslations
@@ -169,7 +131,7 @@ class OC_L10N implements \OCP\IL10N {
 		if(array_key_exists($app.'::'.$lang, self::$cache)) {
 			$this->translations = self::$cache[$app.'::'.$lang]['t'];
 		} else{
-			$i18nDir = self::findI18nDir($app);
+			$i18nDir = $this->findI18nDir($app);
 			$transFile = strip_tags($i18nDir).strip_tags($lang).'.json';
 			// Texts are in $i18ndir
 			// (Just no need to define date/time format etc. twice)
@@ -391,49 +353,12 @@ class OC_L10N implements \OCP\IL10N {
 		return $this->lang ? $this->lang : self::findLanguage();
 	}
 
-	/**
-	 * find the best language
-	 * @param string $app
-	 * @return string language
-	 *
-	 * If nothing works it returns 'en'
-	 */
-	public static function findLanguage($app = null) {
-		if (self::$language != '' && self::languageExists($app, self::$language)) {
-			return self::$language;
-		}
-
-		$config = \OC::$server->getConfig();
-		$userId = \OC_User::getUser();
-
-		if($userId && $config->getUserValue($userId, 'core', 'lang')) {
-			$lang = $config->getUserValue($userId, 'core', 'lang');
-			self::$language = $lang;
-			if(self::languageExists($app, $lang)) {
-				return $lang;
-			}
-		}
-
-		$default_language = $config->getSystemValue('default_language', false);
-
-		if($default_language !== false) {
-			return $default_language;
-		}
-
-		$lang = self::setLanguageFromRequest();
-		if($userId && !$config->getUserValue($userId, 'core', 'lang')) {
-			$config->setUserValue($userId, 'core', 'lang', $lang);
-		}
-
-		return $lang;
-	}
-
 	/**
 	 * find the l10n directory
 	 * @param string $app App that needs to be translated
 	 * @return string directory
 	 */
-	protected static function findI18nDir($app) {
+	protected function findI18nDir($app) {
 		// find the i18n dir
 		$i18nDir = OC::$SERVERROOT.'/core/l10n/';
 		if($app != '') {
@@ -448,26 +373,6 @@ class OC_L10N implements \OCP\IL10N {
 		return $i18nDir;
 	}
 
-	/**
-	 * find all available languages for an app
-	 * @param string $app App that needs to be translated
-	 * @return array an array of available languages
-	 * @deprecated 9.0.0 Use \OC::$server->getL10NFactory()->findAvailableLanguages() instead
-	 */
-	public static function findAvailableLanguages($app=null) {
-		return \OC::$server->getL10NFactory()->findAvailableLanguages($app);
-	}
-
-	/**
-	 * @param string $app
-	 * @param string $lang
-	 * @return bool
-	 * @deprecated 9.0.0 Use \OC::$server->getL10NFactory()->languageExists() instead
-	 */
-	public static function languageExists($app, $lang) {
-		return \OC::$server->getL10NFactory()->languageExists($app, $lang);
-	}
-
 	/**
 	 * @return string
 	 * @throws \Punic\Exception\ValueNotInList
@@ -494,4 +399,44 @@ class OC_L10N implements \OCP\IL10N {
 
 		return $locale;
 	}
+
+	/**
+	 * find the best language
+	 * @param string $app
+	 * @return string language
+	 *
+	 * If nothing works it returns 'en'
+	 * @deprecated 9.0.0 Use \OC::$server->getL10NFactory()->findLanguage() instead
+	 */
+	public static function findLanguage($app = null) {
+		return \OC::$server->getL10NFactory()->findLanguage($app);
+	}
+
+	/**
+	 * @return string
+	 * @deprecated 9.0.0 Use \OC::$server->getL10NFactory()->setLanguageFromRequest() instead
+	 */
+	public static function setLanguageFromRequest() {
+		return \OC::$server->getL10NFactory()->setLanguageFromRequest();
+	}
+
+	/**
+	 * find all available languages for an app
+	 * @param string $app App that needs to be translated
+	 * @return array an array of available languages
+	 * @deprecated 9.0.0 Use \OC::$server->getL10NFactory()->findAvailableLanguages() instead
+	 */
+	public static function findAvailableLanguages($app=null) {
+		return \OC::$server->getL10NFactory()->findAvailableLanguages($app);
+	}
+
+	/**
+	 * @param string $app
+	 * @param string $lang
+	 * @return bool
+	 * @deprecated 9.0.0 Use \OC::$server->getL10NFactory()->languageExists() instead
+	 */
+	public static function languageExists($app, $lang) {
+		return \OC::$server->getL10NFactory()->languageExists($app, $lang);
+	}
 }
diff --git a/lib/private/l10n/factory.php b/lib/private/l10n/factory.php
index b130472760..ecc2318893 100644
--- a/lib/private/l10n/factory.php
+++ b/lib/private/l10n/factory.php
@@ -25,12 +25,18 @@
 
 namespace OC\L10N;
 
+use OCP\IConfig;
+use OCP\IRequest;
 use OCP\L10N\IFactory;
 
 /**
  * A factory that generates language instances
  */
 class Factory implements IFactory {
+
+	/** @var string */
+	protected $requestLanguage = '';
+
 	/**
 	 * cached instances
 	 * @var array Structure: Lang => App => \OCP\IL10N
@@ -42,6 +48,21 @@ class Factory implements IFactory {
 	 */
 	protected $availableLanguages = [];
 
+	/** @var IConfig */
+	protected $config;
+
+	/** @var IRequest */
+	protected $request;
+
+	/**
+	 * @param IConfig $config
+	 * @param IRequest $request
+	 */
+	public function __construct(IConfig $config, IRequest $request) {
+		$this->config = $config;
+		$this->request = $request;
+	}
+
 	/**
 	 * Get a language instance
 	 *
@@ -62,6 +83,41 @@ class Factory implements IFactory {
 		return $this->instances[$key][$app];
 	}
 
+	/**
+	 * Find the best language
+	 *
+	 * @param string|null $app App id or null for core
+	 * @return string language If nothing works it returns 'en'
+	 */
+	public function findLanguage($app = null) {
+		if ($this->requestLanguage !== '' && $this->languageExists($app, $this->requestLanguage)) {
+			return $this->requestLanguage;
+		}
+
+		$userId = \OC_User::getUser(); // FIXME not available in non-static?
+
+		if ($userId && $this->config->getUserValue($userId, 'core', 'lang')) {
+			$lang = $this->config->getUserValue($userId, 'core', 'lang');
+			$this->requestLanguage = $lang;
+			if ($this->languageExists($app, $lang)) {
+				return $lang;
+			}
+		}
+
+		$defaultLanguage = $this->config->getSystemValue('default_language', false);
+
+		if ($defaultLanguage !== false) {
+			return $defaultLanguage;
+		}
+
+		$lang = $this->setLanguageFromRequest($app);
+		if ($userId && $app === null && !$this->config->getUserValue($userId, 'core', 'lang')) {
+			$this->config->setUserValue($userId, 'core', 'lang', $lang);
+		}
+
+		return $lang;
+	}
+
 	/**
 	 * Find all available languages for an app
 	 *
@@ -110,6 +166,50 @@ class Factory implements IFactory {
 		return array_search($lang, $languages);
 	}
 
+	/**
+	 * @param string|null $app App id or null for core
+	 * @return string
+	 */
+	public function setLanguageFromRequest($app = null) {
+		$header = $this->request->getHeader('ACCEPT_LANGUAGE');
+		if ($header) {
+			$available = $this->findAvailableLanguages($app);
+
+			// E.g. make sure that 'de' is before 'de_DE'.
+			sort($available);
+
+			$preferences = preg_split('/,\s*/', strtolower($header));
+			foreach ($preferences as $preference) {
+				list($preferred_language) = explode(';', $preference);
+				$preferred_language = str_replace('-', '_', $preferred_language);
+
+				foreach ($available as $available_language) {
+					if ($preferred_language === strtolower($available_language)) {
+						if ($app === null && !$this->requestLanguage) {
+							$this->requestLanguage = $available_language;
+						}
+						return $available_language;
+					}
+				}
+
+				// Fallback from de_De to de
+				foreach ($available as $available_language) {
+					if (substr($preferred_language, 0, 2) === $available_language) {
+						if ($app === null && !$this->requestLanguage) {
+							$this->requestLanguage = $available_language;
+						}
+						return $available_language;
+					}
+				}
+			}
+		}
+
+		if (!$this->requestLanguage) {
+			$this->requestLanguage = 'en';
+		}
+		return 'en'; // Last try: English
+	}
+
 	/**
 	 * find the l10n directory
 	 *
diff --git a/lib/private/server.php b/lib/private/server.php
index b8f4bdb53f..81929d0c7b 100644
--- a/lib/private/server.php
+++ b/lib/private/server.php
@@ -262,8 +262,11 @@ class Server extends ServerContainer implements IServerContainer {
 		$this->registerService('AppConfig', function (Server $c) {
 			return new \OC\AppConfig($c->getDatabaseConnection());
 		});
-		$this->registerService('L10NFactory', function ($c) {
-			return new \OC\L10N\Factory();
+		$this->registerService('L10NFactory', function (Server $c) {
+			return new \OC\L10N\Factory(
+				$c->getConfig(),
+				$c->getRequest()
+			);
 		});
 		$this->registerService('URLGenerator', function (Server $c) {
 			$config = $c->getConfig();
diff --git a/lib/public/l10n/ifactory.php b/lib/public/l10n/ifactory.php
index 09c75e9af7..2d6f8e873c 100644
--- a/lib/public/l10n/ifactory.php
+++ b/lib/public/l10n/ifactory.php
@@ -34,6 +34,15 @@ interface IFactory {
 	 */
 	public function get($app, $lang = null);
 
+	/**
+	 * Find the best language
+	 *
+	 * @param string|null $app App id or null for core
+	 * @return string language If nothing works it returns 'en'
+	 * @since 9.0.0
+	 */
+	public function findLanguage($app = null);
+
 	/**
 	 * Find all available languages for an app
 	 *
@@ -50,4 +59,11 @@ interface IFactory {
 	 * @since 9.0.0
 	 */
 	public function languageExists($app, $lang);
+
+	/**
+	 * @param string|null $app App id or null for core
+	 * @return string
+	 * @since 9.0.0
+	 */
+	public function setLanguageFromRequest($app = null);
 }
diff --git a/ocs/v1.php b/ocs/v1.php
index 4371b0b604..39a8f4e468 100644
--- a/ocs/v1.php
+++ b/ocs/v1.php
@@ -46,7 +46,7 @@ try {
 	OC_App::loadApps();
 
 	// force language as given in the http request
-	\OC_L10N::setLanguageFromRequest();
+	\OC::$server->getL10NFactory()->setLanguageFromRequest();
 
 	OC::$server->getRouter()->match('/ocs'.\OC::$server->getRequest()->getRawPathInfo());
 } catch (ResourceNotFoundException $e) {
diff --git a/remote.php b/remote.php
index a145fc4bd8..26203e2df8 100644
--- a/remote.php
+++ b/remote.php
@@ -109,7 +109,7 @@ try {
 	}
 
 	// force language as given in the http request
-	\OC_L10N::setLanguageFromRequest();
+	\OC::$server->getL10NFactory()->setLanguageFromRequest();
 
 	$file=ltrim($file, '/');
 
diff --git a/tests/lib/l10n.php b/tests/lib/l10n.php
index d77548c5bf..eb0d911751 100644
--- a/tests/lib/l10n.php
+++ b/tests/lib/l10n.php
@@ -157,7 +157,7 @@ class Test_L10n extends \Test\TestCase {
 	}
 
 	public function testFactoryGetLanguageCode() {
-		$factory = new \OC\L10N\Factory();
+		$factory = new \OC\L10N\Factory($this->getMock('OCP\IConfig'), $this->getMock('OCP\IRequest'));
 		$l = $factory->get('lib', 'de');
 		$this->assertEquals('de', $l->getLanguageCode());
 	}