diff --git a/lib/private/TemplateLayout.php b/lib/private/TemplateLayout.php
index 3acdae0e39575b193a33f24ffd41959db9d54a88..d37a8bbabbe892212d4b4c071e1a3c6e2fe19007 100644
--- a/lib/private/TemplateLayout.php
+++ b/lib/private/TemplateLayout.php
@@ -128,7 +128,9 @@ class TemplateLayout extends \OC_Template {
 
 		}
 		// Send the language to our layouts
-		$this->assign('language', \OC::$server->getL10NFactory()->findLanguage());
+		$lang = \OC::$server->getL10NFactory()->findLanguage();
+		$lang = str_replace('_', '-', $lang);
+		$this->assign('language', $lang);
 
 		if(\OC::$server->getSystemConfig()->getValue('installed', false)) {
 			if (empty(self::$versionHash)) {