diff --git a/composer.json b/composer.json
index 889f837..714e12e 100644
--- a/composer.json
+++ b/composer.json
@@ -28,10 +28,11 @@
         "psr/container": "^1.1 || ^2.0.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^10.2",
+        "boundwize/structarmed": "^0.18.11",
+        "laminas/laminas-coding-standard": "^2.5",
         "phpstan/phpstan": "^2.1.33",
         "phpstan/phpstan-phpunit": "^2.0.10",
-        "laminas/laminas-coding-standard": "^2.5"
+        "phpunit/phpunit": "^10.2"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/Totp.php b/src/Totp.php
index bc450c3..e7ba0b4 100644
--- a/src/Totp.php
+++ b/src/Totp.php
@@ -190,7 +190,7 @@ public function generateRecoveryCodes(int $count = 8, int $length = 10, string $
 
     public function hashRecoveryCodes(array $codes): array
     {
-        return array_map(fn($code) => password_hash($code, PASSWORD_DEFAULT), $codes);
+        return array_map(static fn($code) => password_hash($code, PASSWORD_DEFAULT), $codes);
     }
 
     public function validateRecoveryCode(string $inputCode, array &$hashedCodes): bool
diff --git a/structarmed.php b/structarmed.php
new file mode 100644
index 0000000..ba99065
--- /dev/null
+++ b/structarmed.php
@@ -0,0 +1,25 @@
+<?php
+
+declare(strict_types=1);
+
+use Boundwize\StructArmed\Architecture;
+use Boundwize\StructArmed\Preset\Preset;
+use Boundwize\StructArmed\Rule\Rules\Class_\MustBeFinalRule;
+
+return Architecture::define()
+    ->withPresets(Preset::PSR4(), Preset::CODEQUALITY())
+
+    ->layer('Totp', 'src/Totp.php')
+    ->layer('TotpFactory', 'src/TotpFactory.php')
+    ->layer('ConfigProvider', 'src/ConfigProvider.php')
+    ->ruleset([
+        'Totp'           => [],
+        'TotpFactory'    => ['Totp'],
+        'ConfigProvider' => ['+TotpFactory'],
+    ])
+
+    ->layer('tests', 'test')
+    ->rule(
+        'tests_must_be_final',
+        new MustBeFinalRule(layer: 'tests')
+    );
diff --git a/test/ConfigProviderTest.php b/test/ConfigProviderTest.php
index 96f189f..73aa791 100644
--- a/test/ConfigProviderTest.php
+++ b/test/ConfigProviderTest.php
@@ -9,7 +9,7 @@
 use Dot\Totp\TotpFactory;
 use PHPUnit\Framework\TestCase;
 
-class ConfigProviderTest extends TestCase
+final class ConfigProviderTest extends TestCase
 {
     private ConfigProvider $provider;
 
diff --git a/test/TotpFactoryTest.php b/test/TotpFactoryTest.php
index 0131e97..063b6ec 100644
--- a/test/TotpFactoryTest.php
+++ b/test/TotpFactoryTest.php
@@ -11,7 +11,7 @@
 use Psr\Container\ContainerInterface;
 use Psr\Container\NotFoundExceptionInterface;
 
-class TotpFactoryTest extends TestCase
+final class TotpFactoryTest extends TestCase
 {
     /**
      * @throws ContainerExceptionInterface
diff --git a/test/TotpTest.php b/test/TotpTest.php
index ac3770e..8481919 100644
--- a/test/TotpTest.php
+++ b/test/TotpTest.php
@@ -12,7 +12,7 @@
 use function password_verify;
 use function strlen;
 
-class TotpTest extends TestCase
+final class TotpTest extends TestCase
 {
     public function testConstructorDefaults(): void
     {