diff --git a/rector.php b/rector.php
index 0ef9397..20d190e 100644
--- a/rector.php
+++ b/rector.php
@@ -15,6 +15,6 @@
     ]);
     $rectorConfig->sets([
         LevelSetList::UP_TO_PHP_83,
-        DowngradeLevelSetList::DOWN_TO_PHP_81,
+        // DowngradeLevelSetList::DOWN_TO_PHP_81,
     ]);
 };
diff --git a/src/Configuration/Configuration.php b/src/Configuration/Configuration.php
index c783f16..7849f40 100644
--- a/src/Configuration/Configuration.php
+++ b/src/Configuration/Configuration.php
@@ -4,9 +4,9 @@
 
 namespace App\Configuration;
 
-final class Configuration
+final readonly class Configuration
 {
-    protected readonly array $options;
+    protected array $options;
 
     /**
      * @use
diff --git a/tests/Configuration/ConfigurationTest.php b/tests/Configuration/ConfigurationTest.php
index eb1dcc6..769d61b 100644
--- a/tests/Configuration/ConfigurationTest.php
+++ b/tests/Configuration/ConfigurationTest.php
@@ -9,13 +9,39 @@
  */
 class ConfigurationTest extends TestCase
 {
-    const string DEFAULT_ENV_GITHUB_WORKSPACE = '/usr/bin/app';
-    const string OTHER_ENV_GITHUB_WORKSPACE = '/app';
-    const string OTHER_ENV_BUILD_DIRECTORY_NAME = '.build_directory';
-    const string OTHER_ENV_BUILD_FILE_NAME = 'build_file.zip';
+    /**
+     * @var string
+     */
+    private const string DEFAULT_ENV_GITHUB_WORKSPACE = '/usr/bin/app';
+
+    /**
+     * @var string
+     */
+    private const string DEFAULT_ENV_BUILD_DIRECTORY_NAME = '.build';
+
+    /**
+     * @var string
+     */
+    private const string DEFAULT_ENV_BUILD_FILE_NAME = 'package.zip';
+
+    /**
+     * @var string
+     */
+    private const string OTHER_ENV_GITHUB_WORKSPACE = '/app';
+
+    /**
+     * @var string
+     */
+    private const string OTHER_ENV_BUILD_DIRECTORY_NAME = '.build_directory';
+
+    /**
+     * @var string
+     */
+    private const string OTHER_ENV_BUILD_FILE_NAME = 'build_file.zip';
 
     protected Configuration $configuration;
 
+    #[\Override]
     protected function setUp(): void
     {
         putenv('GITHUB_WORKSPACE=' . self::DEFAULT_ENV_GITHUB_WORKSPACE);
@@ -29,8 +55,14 @@ protected function setUp(): void
      */
     public function testCheckDefaultOptionRoot()
     {
+        putenv('GITHUB_WORKSPACE=' . self::DEFAULT_ENV_GITHUB_WORKSPACE);
+        putenv('BUILD_DIRECTORY_NAME=' . self::DEFAULT_ENV_BUILD_DIRECTORY_NAME);
+        putenv('BUILD_FILE_NAME=' . self::DEFAULT_ENV_BUILD_FILE_NAME);
+
+        $configuration = new Configuration();
+
         $this->assertEquals(
-            $this->configuration->get('root'),
+            $configuration->get('root'),
             self::DEFAULT_ENV_GITHUB_WORKSPACE
         );
     }
@@ -41,9 +73,15 @@ public function testCheckDefaultOptionRoot()
      */
     public function testCheckDefaultOptionBuildDirectory()
     {
+        putenv('GITHUB_WORKSPACE=' . self::DEFAULT_ENV_GITHUB_WORKSPACE);
+        putenv('BUILD_DIRECTORY_NAME=' . self::DEFAULT_ENV_BUILD_DIRECTORY_NAME);
+        putenv('BUILD_FILE_NAME=' . self::DEFAULT_ENV_BUILD_FILE_NAME);
+
+        $configuration = new Configuration();
+
         $this->assertEquals(
-            $this->configuration->get('build.directory'),
-            self::DEFAULT_ENV_GITHUB_WORKSPACE . '/.build'
+            $configuration->get('build.directory'),
+            self::DEFAULT_ENV_GITHUB_WORKSPACE . DIRECTORY_SEPARATOR . self::DEFAULT_ENV_BUILD_DIRECTORY_NAME
         );
     }
 
@@ -53,9 +91,16 @@ public function testCheckDefaultOptionBuildDirectory()
      */
     public function testCheckDefaultOptionBuildFile()
     {
+        putenv('GITHUB_WORKSPACE=' . self::DEFAULT_ENV_GITHUB_WORKSPACE);
+        putenv('BUILD_DIRECTORY_NAME=' . self::DEFAULT_ENV_BUILD_DIRECTORY_NAME);
+        putenv('BUILD_FILE_NAME=' . self::DEFAULT_ENV_BUILD_FILE_NAME);
+
+        $configuration = new Configuration();
+
         $this->assertEquals(
-            $this->configuration->get('build.file'),
-            self::DEFAULT_ENV_GITHUB_WORKSPACE . '/.build/package.zip'
+            $configuration->get('build.file'),
+            self::DEFAULT_ENV_GITHUB_WORKSPACE . DIRECTORY_SEPARATOR . self::DEFAULT_ENV_BUILD_DIRECTORY_NAME .
+             DIRECTORY_SEPARATOR . self::DEFAULT_ENV_BUILD_FILE_NAME
         );
     }
 
@@ -66,6 +111,8 @@ public function testCheckDefaultOptionBuildFile()
     public function testCheckOtherOptionRoot()
     {
         putenv('GITHUB_WORKSPACE=' . self::OTHER_ENV_GITHUB_WORKSPACE);
+        putenv('BUILD_DIRECTORY_NAME=' . self::OTHER_ENV_BUILD_DIRECTORY_NAME);
+        putenv('BUILD_FILE_NAME=' . self::OTHER_ENV_BUILD_FILE_NAME);
 
         $configuration = new Configuration();
 
@@ -83,6 +130,7 @@ public function testCheckOtherOptionBuildDirectory()
     {
         putenv('GITHUB_WORKSPACE=' . self::OTHER_ENV_GITHUB_WORKSPACE);
         putenv('BUILD_DIRECTORY_NAME=' . self::OTHER_ENV_BUILD_DIRECTORY_NAME);
+        putenv('BUILD_FILE_NAME=' . self::OTHER_ENV_BUILD_FILE_NAME);
 
         $configuration = new Configuration();