diff --git a/resources/lang/sl_SI/firefly.php b/resources/lang/sl_SI/firefly.php
index 331cdaf638..7147f5c160 100644
--- a/resources/lang/sl_SI/firefly.php
+++ b/resources/lang/sl_SI/firefly.php
@@ -1,4 +1,6 @@
 <?php
+declare(strict_types=1);
+
 /**
  * firefly.php
  * Copyright (C) 2016 thegrumpydictator@gmail.com