diff --git a/tests/PercentageTest.php b/tests/PercentageTest.php
index 17ae2df..1e87e10 100644
--- a/tests/PercentageTest.php
+++ b/tests/PercentageTest.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Mattiasgeniar\Percentage\Tests;
 
 use Mattiasgeniar\Percentage\Percentage;