diff --git a/tests/docker/mysqlmb4.config.php b/tests/docker/mysqlmb4.config.php
index 528673950a..3511e3c372 100644
--- a/tests/docker/mysqlmb4.config.php
+++ b/tests/docker/mysqlmb4.config.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 $CONFIG = [
 	'mysql.utf8mb4' => true,
 ];