diff --git a/tests/PHPUnit/bootstrap.php b/tests/PHPUnit/bootstrap.php
index 5b2a9f4..776f1c3 100644
--- a/tests/PHPUnit/bootstrap.php
+++ b/tests/PHPUnit/bootstrap.php
@@ -1,4 +1,7 @@
 <?php
+
+declare(strict_types=1);
+
 putenv('TESTS_PATH='.__DIR__);
 putenv('LIBRARY_PATH='.dirname(__DIR__));
 $vendor = dirname(dirname(dirname(__FILE__))).'/vendor/';