diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 95c6c8d..af71020 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -17,7 +17,7 @@ jobs:
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '8.1'
+          php-version: '8.4'
           tools: php-cs-fixer
 
       - name: PHP Coding Standards Fixer
@@ -28,17 +28,26 @@ jobs:
     name: PHPStan
     steps:
       - uses: actions/checkout@v3
-      - uses: php-actions/composer@v6 # or alternative dependency management
-      - uses: php-actions/phpstan@v3
+
+      # Runs the PHPStan the project depends on, with the command from the Makefile. The
+      # php-actions/phpstan action brings its own version, which cannot be kept in step with
+      # composer.json — and PHPStan 1 cannot parse Symfony 8.
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
         with:
-          path: src/
-          level: 9
+          php-version: '8.4'
+
+      - name: Install dependencies
+        run: composer update --prefer-dist --no-progress
+
+      - name: PHPStan
+        run: vendor/bin/phpstan analyse src --level=9
 
   phpunit:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-versions: ['8.1', '8.2', '8.3']
+        php-versions: ['8.4', '8.5']
         mode: ['high-deps', 'low-deps']
       fail-fast: false
     name: PHP ${{ matrix.php-versions }} tests with ${{ matrix.mode }}
diff --git a/README.md b/README.md
index 9d8993c..a91f1f2 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,11 @@
 
 A Symfony Bundle to use when you want to assert that messages used with Message brokers such like RabbitMQ are compliant with the Zero Downtime Deployment.
 
+## Requirements
+
+- PHP 8.4 and above
+- Symfony 7.4 or 8
+
 ## Getting started
 ### Installation
 First, install the bundle with composer:
diff --git a/composer.json b/composer.json
index 87b6a6e..00f5f86 100644
--- a/composer.json
+++ b/composer.json
@@ -7,17 +7,17 @@
     "minimum-stability": "stable",
     "prefer-stable": true,
     "require": {
-        "php": "^8.1.0",
-        "symfony/console": "^6.2|^7.0"
+        "php": "^8.4",
+        "symfony/console": "^7.4|^8.0"
     },
     "require-dev": {
-        "phpstan/phpstan": "^1.10",
+        "phpstan/phpstan": "^2.1",
         "phpunit/phpunit": "^9.5",
         "friendsofphp/php-cs-fixer": "^3.1",
-        "symfony/browser-kit": "^6.2|^7.0",
-        "symfony/framework-bundle": "^6.2|^7.0",
-        "symfony/yaml": "^6.2|^7.0",
-        "symfony/messenger": "^6.2|^7.0"
+        "symfony/browser-kit": "^7.4|^8.0",
+        "symfony/framework-bundle": "^7.4|^8.0",
+        "symfony/yaml": "^7.4|^8.0",
+        "symfony/messenger": "^7.4|^8.0"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/Factory/MessageGenerator.php b/src/Factory/MessageGenerator.php
index cbb2bbe..905b285 100644
--- a/src/Factory/MessageGenerator.php
+++ b/src/Factory/MessageGenerator.php
@@ -73,7 +73,7 @@ private function forcePropertyValue(object $object, string $property, mixed $val
             $reflectionProperty = $reflectionProperty->getDeclaringClass()->getProperty($property);
         }
 
-        $reflectionProperty->setAccessible(true);
+        // No setAccessible() call: it has had no effect since PHP 8.1 and is deprecated in 8.5.
         $reflectionProperty->setValue($object, $value);
     }
 }
diff --git a/src/Serializer/ZddMessageMessengerSerializer.php b/src/Serializer/ZddMessageMessengerSerializer.php
index 3f3047b..ebb41e6 100644
--- a/src/Serializer/ZddMessageMessengerSerializer.php
+++ b/src/Serializer/ZddMessageMessengerSerializer.php
@@ -21,19 +21,25 @@ public function serialize(object $data): string
 
     public function deserialize(string $data): object
     {
-        /** @var array{body: string, headers?: array<string, string>} $dataArray */
-        $dataArray = \json_decode($data, true, 512, \JSON_THROW_ON_ERROR);
-        if (!\is_array($dataArray)) {
-            throw new \InvalidArgumentException(sprintf('Array expected, %s provided', \gettype($data)));
+        $decoded = \json_decode($data, true, 512, \JSON_THROW_ON_ERROR);
+        if (!\is_array($decoded)) {
+            throw new \InvalidArgumentException(sprintf('Array expected, %s provided', \gettype($decoded)));
         }
 
+        /** @var array{body: string, headers?: array<string, string>} $encodedEnvelope */
+        $encodedEnvelope = $decoded;
+
         try {
-            $envelope = $this->serializer->decode($dataArray);
-            if (!$envelope instanceof Envelope) {
-                throw new \InvalidArgumentException(sprintf('%s expected, %s provided', Envelope::class, \gettype($data)));
+            $message = $this->serializer->decode($encodedEnvelope)->getMessage();
+
+            // Since Symfony 8, PhpSerializer no longer throws when a message cannot be rebuilt:
+            // MessageDecodingFailedException::wrap() returns an envelope carrying the failure as
+            // its message. Earlier versions throw, which the catch below still handles.
+            if ($message instanceof MessageDecodingFailedException) {
+                throw new UnableToDeserializeException(previous: $message);
             }
 
-            return $envelope->getMessage();
+            return $message;
         } catch (MessageDecodingFailedException $e) {
             throw new UnableToDeserializeException(previous: $e);
         }