diff --git a/.github/workflows/run-test.yml b/.github/workflows/run-test.yml
index 8ec0be8..76531a0 100644
--- a/.github/workflows/run-test.yml
+++ b/.github/workflows/run-test.yml
@@ -17,7 +17,7 @@ jobs:
         runs-on: ubuntu-latest
         strategy:
             matrix:
-                php-version: ['8.1', '8.2', '8.3', '8.4']
+                php-version: ['8.2', '8.3', '8.4', '8.5']
         steps:
             - uses: shivammathur/setup-php@v2
               with:
diff --git a/.gitignore b/.gitignore
index f4a98a5..dd601e8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -107,3 +107,4 @@ modules.xml
 
 coverage
 /.php-cs-fixer.cache
+/.phpunit.result.cache
diff --git a/Makefile b/Makefile
index 29a6055..abf3852 100644
--- a/Makefile
+++ b/Makefile
@@ -2,5 +2,5 @@
 test:
 	php vendor/bin/rector
 	php vendor/bin/php-cs-fixer fix --ansi -vvv
-	php vendor/bin/phpunit
 	php vendor/bin/phpstan analyse -c phpstan.neon
+	php vendor/bin/phpunit
diff --git a/composer.json b/composer.json
index d09c151..ea42424 100644
--- a/composer.json
+++ b/composer.json
@@ -10,16 +10,16 @@
         }
     ],
     "require": {
-        "php": ">=8.1",
+        "php": ">=8.2",
         "psr/cache": "^1.0 || ^2.0 || ^3.0",
-        "symfony/serializer": ">=5.4",
-        "symfony/cache": ">=5.4",
+        "symfony/serializer": ">=6.4",
+        "symfony/cache": ">=6.4",
         "doctrine/collections": ">=1.6"
     },
     "require-dev": {
         "phpstan/phpstan": "^2.1.4",
         "phpunit/phpunit": "^9.5",
-        "symfony/property-access": ">=5.4",
+        "symfony/property-access": ">=6.4",
         "friendsofphp/php-cs-fixer": "^3.68",
         "rector/rector": "^2.1"
     },
diff --git a/rector.php b/rector.php
index 71f22d2..b61f05b 100644
--- a/rector.php
+++ b/rector.php
@@ -9,7 +9,7 @@
         __DIR__ . '/src',
         __DIR__ . '/tests',
     ])
-    ->withPhpSets(php81: true)
+    ->withPhpSets(php82: true)
     ->withComposerBased(doctrine: true, phpunit: true, symfony: true)
     ->withTypeCoverageLevel(0)
     ->withDeadCodeLevel(0)
diff --git a/src/AbstractCycleAwareWalker.php b/src/AbstractCycleAwareWalker.php
index 5c0f866..9e84ccc 100644
--- a/src/AbstractCycleAwareWalker.php
+++ b/src/AbstractCycleAwareWalker.php
@@ -6,7 +6,7 @@
 
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
-use Symfony\Component\Serializer\Annotation as Serializer;
+use Symfony\Component\Serializer\Attribute as Serializer;
 
 abstract class AbstractCycleAwareWalker extends AbstractWalker
 {
@@ -23,15 +23,19 @@ abstract class AbstractCycleAwareWalker extends AbstractWalker
      * infinite loop.
      *
      * {@inheritDoc}
+     *
+     * @return Collection<int, static>
+     *
+     * @psalm-return Collection<int, static>
      */
     public function getChildren(): Collection
     {
         $root = $this->getRoot();
         if ($root->registerItem($this->getItem())) {
             return parent::getChildren();
-        } else {
-            return new ArrayCollection();
         }
+
+        return new ArrayCollection();
     }
 
     /**
diff --git a/src/AbstractWalker.php b/src/AbstractWalker.php
index 8133f06..5726be8 100644
--- a/src/AbstractWalker.php
+++ b/src/AbstractWalker.php
@@ -11,7 +11,7 @@
 use RZ\TreeWalker\Definition\StoppableDefinition;
 use RZ\TreeWalker\Exception\WalkerDefinitionNotFound;
 use Symfony\Component\Cache\Adapter\ArrayAdapter;
-use Symfony\Component\Serializer\Annotation as Serializer;
+use Symfony\Component\Serializer\Attribute as Serializer;
 
 abstract class AbstractWalker implements WalkerInterface
 {
@@ -24,7 +24,7 @@ abstract class AbstractWalker implements WalkerInterface
     private WalkerInterface $root;
 
     /**
-     * @var Collection<static>|null
+     * @var Collection<int, static>|null
      */
     #[Serializer\Groups(['children'])]
     private ?Collection $children = null;
@@ -32,10 +32,8 @@ abstract class AbstractWalker implements WalkerInterface
     /**
      * @var int<0,max>|null
      */
-    #[
-        Serializer\Groups(['children_count']),
-        Serializer\SerializedName(serializedName: 'childrenCount')
-    ]
+    #[Serializer\Groups(['children_count'])]
+    #[Serializer\SerializedName(serializedName: 'childrenCount')]
     private ?int $count = null;
 
     #[Serializer\Groups(['walker_metadata'])]
@@ -140,6 +138,10 @@ public function getItem(): ?object
     }
 
     /**
+     * @return Collection<int, static>
+     *
+     * @psalm-return Collection<int, static>
+     *
      * @throws \RuntimeException
      * @throws InvalidArgumentException
      */
@@ -153,6 +155,10 @@ public function getChildren(): Collection
     }
 
     /**
+     * @return Collection<int, static>
+     *
+     * @psalm-return Collection<int, static>
+     *
      * @throws InvalidArgumentException
      */
     private function doGetChildren(): Collection
diff --git a/src/Serializer/TreeWalkerNormalizer.php b/src/Serializer/TreeWalkerNormalizer.php
index ae3ca00..a675772 100644
--- a/src/Serializer/TreeWalkerNormalizer.php
+++ b/src/Serializer/TreeWalkerNormalizer.php
@@ -11,9 +11,9 @@
 use Symfony\Component\Serializer\SerializerAwareInterface;
 use Symfony\Component\Serializer\SerializerInterface;
 
-final class TreeWalkerNormalizer implements NormalizerInterface, DenormalizerInterface, SerializerAwareInterface
+final readonly class TreeWalkerNormalizer implements NormalizerInterface, DenormalizerInterface, SerializerAwareInterface
 {
-    public function __construct(private readonly DenormalizerInterface&NormalizerInterface $decorated)
+    public function __construct(private DenormalizerInterface&NormalizerInterface $decorated)
     {
     }
 
@@ -59,14 +59,12 @@ public function normalize(mixed $object, ?string $format = null, array $context
 
     public function supportsNormalization(mixed $data, ?string $format = null, array $context = []): bool
     {
-        // Symfony 5.4 BC
-        return $this->decorated->supportsNormalization($data, $format);
+        return $this->decorated->supportsNormalization($data, $format, $context);
     }
 
     public function supportsDenormalization(mixed $data, string $type, ?string $format = null, array $context = []): bool
     {
-        // Symfony 5.4 BC
-        return $this->decorated->supportsDenormalization($data, $type, $format);
+        return $this->decorated->supportsDenormalization($data, $type, $format, $context);
     }
 
     /**