diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index d02b22b..fd6cd79 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        php-versions: ['8.1', '8.2']
+        php-versions: ['8.1', '8.2', '8.3']
     steps:
     - uses: actions/checkout@v2
     - name: Install PHP
diff --git a/.php-cs-fixer.dist.php b/.php-cs-fixer.dist.php
index cbd174e..7ee02f5 100644
--- a/.php-cs-fixer.dist.php
+++ b/.php-cs-fixer.dist.php
@@ -4,9 +4,13 @@
 
 $rules = [
     '@Symfony' => true,
-    'new_with_braces' => true,
-    'concat_space' => ['spacing' => 'one'],
-    'array_syntax' => ['syntax' => 'short'],
+    'new_with_parentheses' => true,
+    'concat_space' => [
+        'spacing' => 'one',
+    ],
+    'array_syntax' => [
+        'syntax' => 'short',
+    ],
     'yoda_style' => false,
     'phpdoc_no_empty_return' => false,
     'no_superfluous_phpdoc_tags' => true,
@@ -16,11 +20,20 @@
     'void_return' => true,
     'non_printable_character' => true,
     'modernize_types_casting' => true,
-    'ordered_interfaces' => ['order' => 'alpha', 'direction' => 'ascend'],
+    'ordered_interfaces' => [
+        'order' => 'alpha', 
+        'direction' => 'ascend',
+    ],
     'date_time_immutable' => true,
     'native_constant_invocation' => true,
     'combine_nested_dirname' => true,
-    'native_function_invocation' => ['include' => ['@compiler_optimized'], 'scope' => 'namespaced', 'strict' => true],
+    'native_function_invocation' => [
+        'include' => [
+            '@compiler_optimized',
+        ], 
+        'scope' => 'namespaced', 
+        'strict' => true,
+    ],
     'php_unit_construct' => true,
     'php_unit_dedicate_assert' => true,
     'php_unit_expectation' => true,
diff --git a/LICENSE b/LICENSE
index a8f4eeb..8b50177 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2019 liquetsoft
+Copyright (c) 2019 marvin255
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/docker/php/Dockerfile b/docker/php/Dockerfile
index 347d5ca..f5ee37f 100644
--- a/docker/php/Dockerfile
+++ b/docker/php/Dockerfile
@@ -25,7 +25,7 @@ RUN docker-php-ext-install zip opcache \
     && echo 'xdebug.mode=coverage' >> /usr/local/etc/php/conf.d/docker-php-ext-xdebug.ini
 
 
-RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer  --version=2.5.8 \
+RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer  --version=2.7.6 \
     && mkdir -p /.composer && chmod -Rf 777 /.composer
 
 
diff --git a/psalm.xml b/psalm.xml
index 061f082..b145732 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -16,6 +16,7 @@
 
     <issueHandlers>
         <MixedAssignment errorLevel="suppress"/>
+        <MissingClassConstType errorLevel="suppress"/>
         <PropertyNotSetInConstructor>
             <errorLevel type="suppress">
                 <directory name="./tests"/>
diff --git a/src/JwtSecretFactory.php b/src/JwtSecretFactory.php
index d94892c..470c1ad 100644
--- a/src/JwtSecretFactory.php
+++ b/src/JwtSecretFactory.php
@@ -19,7 +19,7 @@ private function __construct()
     /**
      * Creates object that contains key secret.
      */
-    public static function create(string $secret, string $passPhrase = null): Secret
+    public static function create(string $secret, ?string $passPhrase = null): Secret
     {
         return new SecretBase($secret, $passPhrase);
     }
diff --git a/src/JwtSignerFactory.php b/src/JwtSignerFactory.php
index 42e51ee..a1fa0c7 100644
--- a/src/JwtSignerFactory.php
+++ b/src/JwtSignerFactory.php
@@ -23,7 +23,7 @@ private function __construct()
     /**
      * Creates RSA signer.
      */
-    public static function createRsa(Algorithm $algorithm, Secret $public = null, Secret $private = null): JwtSigner
+    public static function createRsa(Algorithm $algorithm, ?Secret $public = null, ?Secret $private = null): JwtSigner
     {
         $implementation = $algorithm->getImplementation();
         if (!is_subclass_of($implementation, Rsa::class)) {
diff --git a/src/JwtValidator.php b/src/JwtValidator.php
index 612be30..334ee70 100644
--- a/src/JwtValidator.php
+++ b/src/JwtValidator.php
@@ -17,5 +17,5 @@ interface JwtValidator
      *
      * @param Constraint|Constraint[]|null $constraints
      */
-    public function validate(Jwt $token, Constraint|array $constraints = null): ValidationResult;
+    public function validate(Jwt $token, Constraint|array|null $constraints = null): ValidationResult;
 }
diff --git a/src/Signer/SecretBase.php b/src/Signer/SecretBase.php
index c40718e..1608f1a 100644
--- a/src/Signer/SecretBase.php
+++ b/src/Signer/SecretBase.php
@@ -38,7 +38,7 @@ public function getSecret(): string
         }
 
         $secret = file_get_contents($filePath);
-        if (empty($secret)) {
+        if ($secret === '') {
             throw new SecretFileNotFoundException(sprintf('Secret file %s is empty', $this->secret));
         }
 
diff --git a/src/Validator/Validator.php b/src/Validator/Validator.php
index f335a81..7507fa9 100644
--- a/src/Validator/Validator.php
+++ b/src/Validator/Validator.php
@@ -33,7 +33,7 @@ public function __construct(iterable $defaultConstraints = [])
     /**
      * {@inheritDoc}
      */
-    public function validate(Jwt $token, Constraint|array $constraints = null): ValidationResult
+    public function validate(Jwt $token, Constraint|array|null $constraints = null): ValidationResult
     {
         $constraintsForValidation = $this->defineConstraintsList($constraints);