diff --git a/.github/workflows/main.yaml b/.github/workflows/main.yaml
index 1ec8cb4..64c9ff3 100644
--- a/.github/workflows/main.yaml
+++ b/.github/workflows/main.yaml
@@ -6,16 +6,15 @@ on:
 
 jobs:
   tests:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     strategy:
       matrix:
-        php: ['7.1', '7.2', '7.3', '7.4', '8.0', '8.1', '8.2', '8.3']
+        php: ['7.4', '8.0', '8.1', '8.2', '8.3', '8.4', '8.5']
     name: PHP ${{ matrix.php }}
     steps:
-      -   uses: actions/checkout@v3
-      # required for "git tag" presence for MonorepoBuilder split and ChangelogLinker git tags resolver; default is 1
-      -   run: git fetch --depth=100000 origin
-      # see https://github.com/shivammathur/setup-php
+      -   uses: actions/checkout@v6
+          with:
+            fetch-depth: 5
       -   uses: shivammathur/setup-php@v2
           with:
             php-version: ${{ matrix.php }}
@@ -26,14 +25,14 @@ jobs:
 
   tests_lowest_dependencies:
     name: Lowest dependencies
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
-      -   uses: actions/checkout@v3
-      -   run: git fetch --depth=100000 origin
-      # see https://github.com/shivammathur/setup-php
+      -   uses: actions/checkout@v6
+          with:
+            fetch-depth: 5
       -   uses: shivammathur/setup-php@v2
           with:
-            php-version: '7.1'
+            php-version: '7.4'
             extensions: xml
             coverage: none
       -   run: composer update --no-progress --prefer-lowest
@@ -41,14 +40,14 @@ jobs:
 
   test_coverage:
     name: Coverage
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
-      -   uses: actions/checkout@v3
-      -   run: git fetch --depth=100000 origin
-      # see https://github.com/shivammathur/setup-php
+      -   uses: actions/checkout@v6
+          with:
+            fetch-depth: 5
       -   uses: shivammathur/setup-php@v2
           with:
-            php-version: '7.1'
+            php-version: '7.4'
             extensions: xml, xdebug
             coverage: xdebug
       -   run: composer install --no-progress
@@ -59,13 +58,14 @@ jobs:
 
   php-cs-fixer:
     name: PHP CS Fixer
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
-      -   uses: actions/checkout@v3
-      # see https://github.com/shivammathur/setup-php
+      -   uses: actions/checkout@v6
+          with:
+            fetch-depth: 5
       -   uses: shivammathur/setup-php@v2
           with:
-            php-version: '8.2'
+            php-version: '8.4'
             extensions: xml
             coverage: none
       -   run: composer install --no-progress
@@ -73,12 +73,14 @@ jobs:
 
   phpstan:
     name: PHPStan
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-24.04
     steps:
-      -   uses: actions/checkout@v3
+      -   uses: actions/checkout@v6
+          with:
+            fetch-depth: 5
       -   uses: shivammathur/setup-php@v2
           with:
-            php-version: '8.2'
+            php-version: '8.4'
             coverage: none
       -   run: composer install --no-progress
       -   run: composer phpstan
\ No newline at end of file
diff --git a/.php-cs-fixer.php b/.php-cs-fixer.php
index 750f3ae..d4a1a25 100644
--- a/.php-cs-fixer.php
+++ b/.php-cs-fixer.php
@@ -1,33 +1,36 @@
 <?php
 
-$finder = PhpCsFixer\Finder::create()
+use PhpCsFixer\Config;
+use PhpCsFixer\Finder;
+use PhpCsFixer\Runner\Parallel\ParallelConfigFactory;
+
+$finder = Finder::create()
     ->exclude('vendor')
     ->in(__DIR__)
 ;
 
-$config = new PhpCsFixer\Config();
-return $config->setRules([
-    '@PSR12' => true,
-    '@PSR12:risky' => true,
-    '@PhpCsFixer' => true,
-    '@PhpCsFixer:risky' => true,
-    '@PHP71Migration' => true,
-    '@PHP71Migration:risky' => true,
-    'array_syntax' => ['syntax' => 'short'],
-    'php_unit_test_class_requires_covers' => false,
-    'backtick_to_shell_exec' => true,
-    'blank_line_before_statement' => [
-        'statements' => ['declare', 'return', 'case'],
-    ],
-    'comment_to_phpdoc' => false,
-    'declare_equal_normalize' => ['space' => 'single'],
-    'global_namespace_import' => true,
-    'linebreak_after_opening_tag' => true,
-    'native_function_invocation' => false,
-    'no_unset_on_property' => false,
-    'php_unit_test_case_static_method_calls' => ['call_type' => 'self'],
-    'phpdoc_to_comment' => false,
-    'self_static_accessor' => true,
-])
-    ->setFinder($finder)
-    ;
\ No newline at end of file
+$config = new Config();
+return $config
+    ->setParallelConfig(ParallelConfigFactory::detect())
+    ->setRules([
+        '@auto' => true,
+        '@auto:risky' => true,
+        '@PhpCsFixer' => true,
+        '@PhpCsFixer:risky' => true,
+        'array_syntax' => ['syntax' => 'short'],
+        'php_unit_test_class_requires_covers' => false,
+        'backtick_to_shell_exec' => true,
+        'blank_line_before_statement' => [
+            'statements' => ['declare', 'return', 'case'],
+        ],
+        'comment_to_phpdoc' => false,
+        'declare_equal_normalize' => ['space' => 'single'],
+        'global_namespace_import' => true,
+        'linebreak_after_opening_tag' => true,
+        'native_function_invocation' => false,
+        'no_unset_on_property' => false,
+        'php_unit_test_case_static_method_calls' => ['call_type' => 'self'],
+        'phpdoc_to_comment' => false,
+        'self_static_accessor' => true,
+    ])
+    ->setFinder($finder);
diff --git a/composer.json b/composer.json
index e39ee9c..8b1396c 100644
--- a/composer.json
+++ b/composer.json
@@ -16,20 +16,20 @@
     }
   ],
   "require": {
-    "php": "^7.1 || ^8.0",
+    "php": "^7.4 || ^8.0",
     "ext-dom": "*",
     "ext-filter": "*",
     "ext-libxml": "*",
     "ext-simplexml": "*",
-    "webmozart/assert": "^1.5"
+    "webmozart/assert": "^1.5 || ^2.0"
   },
   "require-dev": {
-    "friendsofphp/php-cs-fixer": "^3.0",
-    "phpstan/phpstan": "^1.0",
-    "phpstan/phpstan-phpunit": "^1.0",
-    "phpstan/phpstan-strict-rules": "^1.0",
-    "phpstan/phpstan-webmozart-assert": "^1.0",
-    "phpunit/phpunit": "^7.0 || ^8.0 || ^9.0"
+    "friendsofphp/php-cs-fixer": "^3.92",
+    "phpstan/phpstan": "^2.0",
+    "phpstan/phpstan-phpunit": "^2.0",
+    "phpstan/phpstan-strict-rules": "^2.0",
+    "phpstan/phpstan-webmozart-assert": "^2.0",
+    "phpunit/phpunit": "^9.1 || ^10.0"
   },
   "config": {
     "sort-packages": true
diff --git a/example/feed.php b/example/feed.php
index 59915bf..4021daf 100644
--- a/example/feed.php
+++ b/example/feed.php
@@ -5,7 +5,7 @@
 use AtomGenerator\Entry;
 use AtomGenerator\Feed;
 
-include_once 'vendor/autoload.php';
+include_once __DIR__.'/../vendor/autoload.php';
 
 $entry = new Entry();
 $entry->setTitle('Post', 'text');
diff --git a/phpunit.xml b/phpunit.xml
index 01dcc3a..4d0e0cc 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -3,12 +3,12 @@
          xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
          bootstrap="vendor/autoload.php"
          colors="true">
-    <coverage>
+    <source>
         <include>
             <directory suffix=".php">src</directory>
             <directory suffix=".php">tests</directory>
         </include>
-    </coverage>
+    </source>
     <testsuites>
         <testsuite name="default">
             <directory>tests</directory>
diff --git a/src/AbstractElement.php b/src/AbstractElement.php
index 31ddbd2..f06334a 100644
--- a/src/AbstractElement.php
+++ b/src/AbstractElement.php
@@ -12,35 +12,29 @@
 
 abstract class AbstractElement
 {
-    /** @var string */
-    protected $id;
+    protected string $id;
 
-    /** @var string */
-    protected $title;
+    protected string $title;
 
-    /** @var null|string */
-    protected $titleType;
+    protected ?string $titleType = null;
 
-    /** @var DateTimeInterface */
-    protected $updatedDateTime;
+    protected DateTimeInterface $updatedDateTime;
 
-    /** @var null|string */
-    protected $rights;
+    protected ?string $rights = null;
 
-    /** @var null|string */
-    protected $rightsType;
+    protected ?string $rightsType = null;
 
     /** @var string[][] */
-    protected $authors = [];
+    protected array $authors = [];
 
     /** @var string[][] */
-    protected $contributors = [];
+    protected array $contributors = [];
 
     /** @var string[][] */
-    protected $categories = [];
+    protected array $categories = [];
 
     /** @var string[][] */
-    protected $links = [];
+    protected array $links = [];
 
     /**
      * AbstractElement constructor.
diff --git a/src/Entry.php b/src/Entry.php
index 9ef23d0..680c42b 100644
--- a/src/Entry.php
+++ b/src/Entry.php
@@ -10,26 +10,19 @@
 
 class Entry extends AbstractElement
 {
-    /** @var null|string */
-    protected $summary;
+    protected ?string $summary = null;
 
-    /** @var null|string */
-    protected $summaryType;
+    protected ?string $summaryType = null;
 
-    /** @var null|string */
-    protected $content;
+    protected ?string $content = null;
 
-    /** @var null|string */
-    protected $contentType;
+    protected ?string $contentType = null;
 
-    /** @var null|string */
-    protected $contentSrc;
+    protected ?string $contentSrc = null;
 
-    /** @var null|DateTimeInterface */
-    protected $publishedDateTime;
+    protected ?DateTimeInterface $publishedDateTime = null;
 
-    /** @var null|Feed */
-    protected $source;
+    protected ?Feed $source = null;
 
     public function setSummary(?string $summary, ?string $type = null): void
     {
diff --git a/src/Feed.php b/src/Feed.php
index abd0c70..532d018 100644
--- a/src/Feed.php
+++ b/src/Feed.php
@@ -5,6 +5,7 @@
 namespace AtomGenerator;
 
 use DOMDocument;
+use Exception;
 use LibXMLError;
 use SimpleXMLElement;
 use Webmozart\Assert\Assert;
@@ -12,38 +13,30 @@
 class Feed extends AbstractElement
 {
     /** @var Entry[] */
-    protected $entries = [];
+    protected array $entries = [];
 
-    /** @var bool */
-    protected $prettify = false;
+    protected bool $prettify = false;
 
-    /** @var null|string */
-    protected $language;
+    protected ?string $language = null;
 
-    /** @var null|string */
-    protected $subtitle;
+    protected ?string $subtitle = null;
 
-    /** @var null|string */
-    protected $icon;
+    protected ?string $icon = null;
 
-    /** @var null|string */
-    protected $logo;
+    protected ?string $logo = null;
 
-    /** @var null|string */
-    protected $generator;
+    protected ?string $generator = null;
 
-    /** @var null|string */
-    protected $generatorVersion;
+    protected ?string $generatorVersion = null;
 
-    /** @var null|string */
-    protected $generatorUri;
+    protected ?string $generatorUri = null;
 
     /**
      * @var array[]
      *
      * @phpstan-var array<array{ns: string, uri: string, name: string, value: string, attributes: string[]}>
      */
-    protected $customElements = [];
+    protected array $customElements = [];
 
     /**
      * Feed constructor.
@@ -174,6 +167,9 @@ public function addChildrenTo(SimpleXMLElement $parent): void
         }
     }
 
+    /**
+     * @throws Exception
+     */
     public function getSimpleXML(): SimpleXMLElement
     {
         $attributes = [];
diff --git a/tests/FeedTest.php b/tests/FeedTest.php
index 422d3cc..9f0e25d 100644
--- a/tests/FeedTest.php
+++ b/tests/FeedTest.php
@@ -17,12 +17,15 @@
 final class FeedTest extends TestCase
 {
     protected const TEST_FEED_XML_PATH_1 = __DIR__.'/feed_1.xml';
+
     protected const TEST_FEED_XML_PATH_2 = __DIR__.'/feed_2.xml';
+
     protected const TEST_FEED_XML_PATH_3 = __DIR__.'/feed_3.xml';
+
     protected const TEST_FEED_XML_PATH_4 = __DIR__.'/feed_4.xml';
 
     /** @var bool reset file contents */
-    protected static $reset = false;
+    protected static bool $reset = false;
 
     public function testFeedCreation1(): void
     {
@@ -67,7 +70,7 @@ public function testFeedCreation1(): void
         }
 
         $valid = Feed::validate($feed->getDocument(), $errors);
-        self::assertTrue($valid, self::formatXmlErrors($errors));
+        self::assertTrue($valid, self::formatXmlErrors($errors ?? []));
 
         $xml = $feed->saveXML();
         assert(false !== $xml);
@@ -99,7 +102,7 @@ public function testFeedCreation2(): void
         }
 
         $valid = Feed::validate($feed->getDocument(), $errors);
-        self::assertTrue($valid, self::formatXmlErrors($errors));
+        self::assertTrue($valid, self::formatXmlErrors($errors ?? []));
 
         $xml = $feed->saveXML();
         assert(false !== $xml);
@@ -127,7 +130,7 @@ public function testFeedCreation3(): void
         }
 
         $valid = Feed::validate($feed->getDocument(), $errors);
-        self::assertTrue($valid, self::formatXmlErrors($errors));
+        self::assertTrue($valid, self::formatXmlErrors($errors ?? []));
 
         $xml = $feed->saveXML();
         assert(false !== $xml);
@@ -161,7 +164,7 @@ public function testFeedCreation4(): void
         }
 
         $valid = Feed::validate($feed->getDocument(), $errors);
-        self::assertTrue($valid, self::formatXmlErrors($errors));
+        self::assertTrue($valid, self::formatXmlErrors($errors ?? []));
 
         $xml = $feed->saveXML();
         assert(false !== $xml);