diff --git a/Classes/Service/MailTemplateService.php b/Classes/Service/MailTemplateService.php
index 2af2a8808e21e9263b3df89219fb31efcd43758b..6fd88127c300056ae80d46001f8da84b440b1393 100644
--- a/Classes/Service/MailTemplateService.php
+++ b/Classes/Service/MailTemplateService.php
@@ -66,7 +66,7 @@ class MailTemplateService {
 	/**
 	 * @var string language
 	 */
-	private $language;
+	private $language = 'de';
 
 	/**
 	 * @var boolean ignoreMailQueue
@@ -196,7 +196,7 @@ class MailTemplateService {
 	 * @param array $registerArray
 	 * @return MailTemplateService
 	 */
-	public static function setRegisterArray($registerArray) {
+	public static function setRegisterArray(array $registerArray) {
 		self::$registerArray = $registerArray;
 	}
 
@@ -290,7 +290,7 @@ class MailTemplateService {
 	 * @param array $content
 	 * @return MailTemplateService
 	 */
-	public function setContent($content) {
+	public function setContent(array $content) {
 		$this->content = $content;
 		return $this;
 	}