diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 92298b9..5c79605 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -53,8 +53,10 @@ jobs:
         strategy:
             matrix:
                 php-version:
+                    - "8.1"
+                    - "8.2"
+                    - "8.3"
                     - "8.4"
-                    - "8.5"
 
                 dependencies:
                     - "lowest"
@@ -87,8 +89,10 @@ jobs:
         strategy:
             matrix:
                 php-version:
+                    - "8.1"
+                    - "8.2"
+                    - "8.3"
                     - "8.4"
-                    - "8.5"
 
                 dependencies:
                     - "lowest"
@@ -121,8 +125,10 @@ jobs:
         strategy:
             matrix:
                 php-version:
+                    - "8.1"
+                    - "8.2"
+                    - "8.3"
                     - "8.4"
-                    - "8.5"
 
                 dependencies:
                     - "lowest"
diff --git a/composer.json b/composer.json
index 7f3118c..7b681e3 100644
--- a/composer.json
+++ b/composer.json
@@ -10,14 +10,23 @@
         }
     ],
     "require": {
-        "php": ">=8.4",
+        "php": ">=8.1",
         "cuyz/valinor": "^2.0",
         "psr/log": "^1.1 || ^2.0 || ^3.0",
         "setono/html-element": "^1.0",
         "symfony/options-resolver": "^6.4 || ^7.0 || ^8.0"
     },
     "require-dev": {
-        "setono/code-quality-pack": "^3.4"
+        "ergebnis/composer-normalize": "^2.45",
+        "infection/infection": "^0.28 || ^0.29 || ^0.32",
+        "phpstan/extension-installer": "^1.4",
+        "phpstan/phpstan": "^2.1",
+        "phpstan/phpstan-phpunit": "^2.0",
+        "phpstan/phpstan-strict-rules": "^2.0",
+        "phpunit/phpunit": "^10.5 || ^11.5",
+        "rector/rector": "^2.0",
+        "shipmonk/composer-dependency-analyser": "^1.8",
+        "sylius-labs/coding-standard": "^4.5"
     },
     "prefer-stable": true,
     "autoload": {
diff --git a/rector.php b/rector.php
index 9ee4fe1..3660d8d 100644
--- a/rector.php
+++ b/rector.php
@@ -12,7 +12,7 @@
         __DIR__ . '/src',
         __DIR__ . '/tests',
     ])
-    ->withPhpSets(php84: true)
+    ->withPhpSets(php81: true)
     ->withAttributesSets(phpunit: true)
     ->withSets([
         PHPUnitSetList::PHPUNIT_100,
diff --git a/src/Block/Image/File.php b/src/Block/Image/File.php
index d798cd4..d89d419 100644
--- a/src/Block/Image/File.php
+++ b/src/Block/Image/File.php
@@ -5,9 +5,9 @@
 namespace Setono\EditorJS\Block\Image;
 
 // todo right now it doesn't support the extra data you can set on the File object (see https://github.com/editor-js/image#providing-custom-uploading-methods)
-final readonly class File
+final class File
 {
-    public function __construct(public string $url)
+    public function __construct(public readonly string $url)
     {
     }
 }
diff --git a/src/Block/ListBlock.php b/src/Block/ListBlock.php
index 3b674c4..3c6c23a 100644
--- a/src/Block/ListBlock.php
+++ b/src/Block/ListBlock.php
@@ -6,9 +6,9 @@
 
 final class ListBlock extends Block
 {
-    public const string STYLE_ORDERED = 'ordered';
+    public const STYLE_ORDERED = 'ordered';
 
-    public const string STYLE_UNORDERED = 'unordered';
+    public const STYLE_UNORDERED = 'unordered';
 
     /**
      * This is a helper property containing the html tag for the list (i.e. ol/ul)
diff --git a/src/BlockRenderer/DelimiterBlockRenderer.php b/src/BlockRenderer/DelimiterBlockRenderer.php
index 6b0ce85..b320017 100644
--- a/src/BlockRenderer/DelimiterBlockRenderer.php
+++ b/src/BlockRenderer/DelimiterBlockRenderer.php
@@ -18,7 +18,7 @@ public function render(Block $block): HtmlElement
 
         $tag = $this->getOption('tag');
 
-        return new HtmlElement(is_string($tag) ? $tag : 'hr')->withClass($this->getClassOption('class'));
+        return (new HtmlElement(is_string($tag) ? $tag : 'hr'))->withClass($this->getClassOption('class'));
     }
 
     /**
@@ -29,7 +29,6 @@ public function supports(Block $block): bool
         return $block instanceof DelimiterBlock;
     }
 
-    #[\Override]
     protected function configureOptions(OptionsResolver $optionsResolver): void
     {
         parent::configureOptions($optionsResolver);
diff --git a/src/BlockRenderer/EmbedBlockRenderer.php b/src/BlockRenderer/EmbedBlockRenderer.php
index 59cff9b..b73630d 100644
--- a/src/BlockRenderer/EmbedBlockRenderer.php
+++ b/src/BlockRenderer/EmbedBlockRenderer.php
@@ -31,7 +31,6 @@ public function render(Block $block): HtmlElement
         )->withClass($this->getClassOption('containerClass'));
     }
 
-    #[\Override]
     protected function configureOptions(OptionsResolver $optionsResolver): void
     {
         parent::configureOptions($optionsResolver);
diff --git a/src/BlockRenderer/HeaderBlockRenderer.php b/src/BlockRenderer/HeaderBlockRenderer.php
index 33810ba..abdadfa 100644
--- a/src/BlockRenderer/HeaderBlockRenderer.php
+++ b/src/BlockRenderer/HeaderBlockRenderer.php
@@ -18,7 +18,7 @@ public function render(Block $block): HtmlElement
     {
         UnsupportedBlockException::assert($this->supports($block), $block, $this);
 
-        return new HtmlElement(sprintf('h%d', $block->level), $block->text)
+        return (new HtmlElement(sprintf('h%d', $block->level), $block->text))
             ->withClass($this->getClassOption('class'))
         ;
     }
diff --git a/src/BlockRenderer/ImageBlockRenderer.php b/src/BlockRenderer/ImageBlockRenderer.php
index 0549c52..9678384 100644
--- a/src/BlockRenderer/ImageBlockRenderer.php
+++ b/src/BlockRenderer/ImageBlockRenderer.php
@@ -48,7 +48,6 @@ public function render(Block $block): HtmlElement
         return $container;
     }
 
-    #[\Override]
     protected function configureOptions(OptionsResolver $optionsResolver): void
     {
         parent::configureOptions($optionsResolver);
diff --git a/src/BlockRenderer/ListBlockRenderer.php b/src/BlockRenderer/ListBlockRenderer.php
index 3f5ba20..3994fd9 100644
--- a/src/BlockRenderer/ListBlockRenderer.php
+++ b/src/BlockRenderer/ListBlockRenderer.php
@@ -19,15 +19,14 @@ public function render(Block $block): HtmlElement
     {
         UnsupportedBlockException::assert($this->supports($block), $block, $this);
 
-        return new HtmlElement($block->tag, ...array_map(
+        return (new HtmlElement($block->tag, ...array_map(
             fn (string $item) => HtmlElement::li($item)->withClass($this->getClassOption('itemClass')),
             $block->items,
-        ))
+        )))
             ->withClass($this->getClassOption('class'))
         ;
     }
 
-    #[\Override]
     protected function configureOptions(OptionsResolver $optionsResolver): void
     {
         parent::configureOptions($optionsResolver);
diff --git a/src/Parser/Parser.php b/src/Parser/Parser.php
index b6a41e8..3174759 100644
--- a/src/Parser/Parser.php
+++ b/src/Parser/Parser.php
@@ -88,7 +88,7 @@ public function parse(string $json): ParserResult
     public function getMapperBuilder(): MapperBuilder
     {
         if (null === $this->mapperBuilder) {
-            $this->mapperBuilder = new MapperBuilder()
+            $this->mapperBuilder = (new MapperBuilder())
                 ->allowSuperfluousKeys()
                 ->allowPermissiveTypes()
             ;
diff --git a/src/Parser/ParserResult.php b/src/Parser/ParserResult.php
index 120a064..2a80058 100644
--- a/src/Parser/ParserResult.php
+++ b/src/Parser/ParserResult.php
@@ -6,13 +6,13 @@
 
 use Setono\EditorJS\Block\Block;
 
-final readonly class ParserResult
+final class ParserResult
 {
     public function __construct(
-        public \DateTimeImmutable $time,
-        public string $version,
+        public readonly \DateTimeImmutable $time,
+        public readonly string $version,
         /** @var list<Block> $blocks */
-        public array $blocks,
+        public readonly array $blocks,
     ) {
     }
 }
diff --git a/tests/Renderer/RendererTest.php b/tests/Renderer/RendererTest.php
index a2286b3..2de7d54 100644
--- a/tests/Renderer/RendererTest.php
+++ b/tests/Renderer/RendererTest.php
@@ -39,7 +39,7 @@ public function it_throws_exception_if_block_is_not_supported(): void
             new HeaderBlock('id', 'Header', 1),
         ]);
 
-        self::assertSame('<h1>Header</h1><p>Lorem ipsum</p>', new Renderer()->render($parserResult));
+        self::assertSame('<h1>Header</h1><p>Lorem ipsum</p>', (new Renderer())->render($parserResult));
     }
 
     #[\PHPUnit\Framework\Attributes\Test]