diff --git a/.phpstan/ExceptionTypeResolver.php b/.phpstan/ExceptionTypeResolver.php
index 38f23114..5c53133f 100644
--- a/.phpstan/ExceptionTypeResolver.php
+++ b/.phpstan/ExceptionTypeResolver.php
@@ -8,7 +8,7 @@
 use PHPStan\Rules\Exceptions\DefaultExceptionTypeResolver;
 use PHPStan\Rules\Exceptions\ExceptionTypeResolver as PHPStanExceptionTypeResolver;
 
-class ExceptionTypeResolver implements PHPStanExceptionTypeResolver
+final class ExceptionTypeResolver implements PHPStanExceptionTypeResolver
 {
     public function __construct(private DefaultExceptionTypeResolver $defaultExceptionTypeResolver)
     {
diff --git a/rector.php b/rector.php
index 76252a68..a2461d73 100644
--- a/rector.php
+++ b/rector.php
@@ -3,6 +3,9 @@
 declare(strict_types=1);
 
 use Rector\Config\RectorConfig;
+use Rector\Privatization\Rector\Class_\FinalizeClassesWithoutChildrenRector;
+use Rector\Privatization\Rector\ClassMethod\PrivatizeFinalClassMethodRector;
+use Rector\Privatization\Rector\Property\PrivatizeFinalClassPropertyRector;
 use Rector\Set\ValueObject\LevelSetList;
 
 return static function (RectorConfig $rectorConfig): void {
@@ -17,6 +20,11 @@
     $rectorConfig->sets([
         LevelSetList::UP_TO_PHP_80,
     ]);
+    $rectorConfig->rules([
+        FinalizeClassesWithoutChildrenRector::class,
+        PrivatizeFinalClassMethodRector::class,
+        PrivatizeFinalClassPropertyRector::class,
+    ]);
 
     $rectorConfig->importNames();
 };
diff --git a/src/Standard/Twig.php b/src/Standard/Twig.php
index 62e73c48..0f7e5492 100644
--- a/src/Standard/Twig.php
+++ b/src/Standard/Twig.php
@@ -14,7 +14,7 @@
  *
  * @see https://twig.symfony.com/doc/3.x/coding_standards.html
  */
-class Twig implements StandardInterface
+final class Twig implements StandardInterface
 {
     public function getRules(): array
     {
diff --git a/tests/File/FinderTest.php b/tests/File/FinderTest.php
index e883ecfb..4bb8d732 100644
--- a/tests/File/FinderTest.php
+++ b/tests/File/FinderTest.php
@@ -7,7 +7,7 @@
 use PHPUnit\Framework\TestCase;
 use TwigCsFixer\File\Finder;
 
-class FinderTest extends TestCase
+final class FinderTest extends TestCase
 {
     public function testFinder(): void
     {
diff --git a/tests/Report/ViolationIdTest.php b/tests/Report/ViolationIdTest.php
index 0ad0eec4..a00bb916 100644
--- a/tests/Report/ViolationIdTest.php
+++ b/tests/Report/ViolationIdTest.php
@@ -7,7 +7,7 @@
 use PHPUnit\Framework\TestCase;
 use TwigCsFixer\Report\ViolationId;
 
-class ViolationIdTest extends TestCase
+final class ViolationIdTest extends TestCase
 {
     /**
      * @dataProvider toStringDataProvider
diff --git a/tests/Report/ViolationTest.php b/tests/Report/ViolationTest.php
index e6c14a8b..93485742 100644
--- a/tests/Report/ViolationTest.php
+++ b/tests/Report/ViolationTest.php
@@ -24,6 +24,19 @@ public function testGetters(): void
         static::assertSame($violationId, $violation->getIdentifier());
     }
 
+    public function testGetterWithoutViolationId(): void
+    {
+        $violation = new Violation(Violation::LEVEL_WARNING, 'message', 'filename', 'name');
+
+        static::assertSame(Violation::LEVEL_WARNING, $violation->getLevel());
+        static::assertSame('message', $violation->getMessage());
+        static::assertSame('filename', $violation->getFilename());
+        static::assertNull($violation->getLine());
+        static::assertNull($violation->getLinePosition());
+        static::assertSame('name', $violation->getRuleName());
+        static::assertNull($violation->getIdentifier());
+    }
+
     /**
      * @dataProvider getLevelAsStringDataProvider
      */
diff --git a/tests/Rules/Fixtures/FakeRule.php b/tests/Rules/Fixtures/FakeRule.php
index a2b1b0f6..f9b5c906 100644
--- a/tests/Rules/Fixtures/FakeRule.php
+++ b/tests/Rules/Fixtures/FakeRule.php
@@ -9,7 +9,7 @@
 /**
  * This rule reports an error for the first token of every line.
  */
-class FakeRule extends AbstractRule
+final class FakeRule extends AbstractRule
 {
     public function process(int $tokenPosition, array $tokens): void
     {