diff --git a/src/Gopay/Gopay.php b/src/Gopay/Gopay.php
index f683892..7845ab3 100644
--- a/src/Gopay/Gopay.php
+++ b/src/Gopay/Gopay.php
@@ -101,6 +101,12 @@ class Gopay extends Object
 	const LANG_CS = 'CS';
 	/** @const English */
 	const LANG_EN = 'EN';
+	/** @const Slovak */
+	const LANG_SK = 'SK';
+	/** @const German */
+	const LANG_DE = 'DE';
+	/** @const Russian */
+	const LANG_RU = 'RU';
 
 	/** @var Config */
 	private $config;
diff --git a/src/Gopay/Service/AbstractService.php b/src/Gopay/Service/AbstractService.php
index 5e1b758..c0516ed 100644
--- a/src/Gopay/Service/AbstractService.php
+++ b/src/Gopay/Service/AbstractService.php
@@ -31,6 +31,9 @@ abstract class AbstractService extends Object
 	protected $allowedLang = [
 		Gopay::LANG_CS,
 		Gopay::LANG_EN,
+		Gopay::LANG_SK,
+		Gopay::LANG_DE,
+		Gopay::LANG_RU,
 	];
 
 	/**