diff --git a/tests/tests/PHPTest.php b/tests/tests/PHPTest.php
index 204cd1f27..c11342069 100644
--- a/tests/tests/PHPTest.php
+++ b/tests/tests/PHPTest.php
@@ -11,7 +11,7 @@
 
 use SebastianBergmann\CodeCoverage\TestCase;
 
-class PHPTest extends TestCase
+final class PHPTest extends TestCase
 {
     protected function tearDown(): void
     {