diff --git a/.scrutinizer.yml b/.scrutinizer.yml
index d754df6..a01d1bd 100644
--- a/.scrutinizer.yml
+++ b/.scrutinizer.yml
@@ -6,7 +6,7 @@ build:
         rabbitmq: false
         mongodb: false
         php:
-            version: 7.3
+            version: 7.4
 
     cache:
         disabled: false
diff --git a/.travis.yml b/.travis.yml
index cf7f671..efc25fb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,8 +3,7 @@ sudo: false
 language: php
 
 php:
-  - 7.3
-  - 7.4snapshot
+  - 7.4
   - nightly
 
 cache:
@@ -22,7 +21,6 @@ script:
 
 jobs:
   allow_failures:
-    - php: 7.4snapshot
     - php: nightly
 
   include:
diff --git a/composer.json b/composer.json
index 1162b97..a34efe4 100644
--- a/composer.json
+++ b/composer.json
@@ -11,24 +11,25 @@
     ],
     "keywords": ["PSR-15", "RFC-7807", "error handling"],
     "require": {
-        "php": "^7.3",
-        "ext-json": "^1.7",
+        "php": "^7.4 || ^8.0",
+        "ext-json": "*",
         "fig/http-message-util": "^1.1",
-        "lcobucci/content-negotiation-middleware": "^2.0",
+        "lcobucci/content-negotiation-middleware": "^2.2",
         "psr/http-factory": "^1.0",
         "psr/http-server-middleware": "^1.0",
         "psr/log": "^1.1"
     },
     "require-dev": {
-        "infection/infection": "^0.13",
-        "lcobucci/coding-standard": "^3.0",
-        "phpstan/phpstan": "^0.11",
-        "phpstan/phpstan-deprecation-rules": "^0.11",
-        "phpstan/phpstan-phpunit": "^0.11",
-        "phpstan/phpstan-strict-rules": "^0.11",
-        "phpunit/phpunit": "^8.2",
-        "squizlabs/php_codesniffer": "^3.4",
-        "zendframework/zend-diactoros": "^2.0"
+        "infection/infection": "^0.15",
+        "laminas/laminas-diactoros": "^2.2",
+        "lcobucci/coding-standard": "^4.0",
+        "phpstan/extension-installer": "^1.0",
+        "phpstan/phpstan": "^0.12",
+        "phpstan/phpstan-deprecation-rules": "^0.12",
+        "phpstan/phpstan-phpunit": "^0.12",
+        "phpstan/phpstan-strict-rules": "^0.12",
+        "phpunit/phpunit": "^9.0",
+        "squizlabs/php_codesniffer": "^3.5"
     },
     "autoload": {
         "psr-4": {
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 46705ff..7c87780 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -1,9 +1,3 @@
-includes:
-    - vendor/phpstan/phpstan-phpunit/extension.neon
-    - vendor/phpstan/phpstan-phpunit/rules.neon
-    - vendor/phpstan/phpstan-deprecation-rules/rules.neon
-    - vendor/phpstan/phpstan-strict-rules/rules.neon
-
 parameters:
     level: 7
     paths:
diff --git a/src/DebugInfoStrategy/NoTrace.php b/src/DebugInfoStrategy/NoTrace.php
index ebf464c..09dab90 100644
--- a/src/DebugInfoStrategy/NoTrace.php
+++ b/src/DebugInfoStrategy/NoTrace.php
@@ -26,6 +26,9 @@ public function extractDebugInfo(Throwable $error): ?array
         return $debugInfo;
     }
 
+    /**
+     * @return Generator<array<string, string|int>>
+     */
     private function streamStack(?Throwable $previous): Generator
     {
         if ($previous === null) {
diff --git a/src/ErrorConversionMiddleware.php b/src/ErrorConversionMiddleware.php
index 461416e..78af67e 100644
--- a/src/ErrorConversionMiddleware.php
+++ b/src/ErrorConversionMiddleware.php
@@ -24,20 +24,9 @@ final class ErrorConversionMiddleware implements MiddlewareInterface
 
     private const STATUS_URL = 'https://httpstatuses.com/';
 
-    /**
-     * @var ResponseFactoryInterface
-     */
-    private $responseFactory;
-
-    /**
-     * @var DebugInfoStrategy
-     */
-    private $debugInfoStrategy;
-
-    /**
-     * @var StatusCodeExtractionStrategy
-     */
-    private $statusCodeExtractor;
+    private ResponseFactoryInterface $responseFactory;
+    private DebugInfoStrategy $debugInfoStrategy;
+    private StatusCodeExtractionStrategy $statusCodeExtractor;
 
     public function __construct(
         ResponseFactoryInterface $responseFactory,
diff --git a/src/ErrorLoggingMiddleware.php b/src/ErrorLoggingMiddleware.php
index c710794..1c9002f 100644
--- a/src/ErrorLoggingMiddleware.php
+++ b/src/ErrorLoggingMiddleware.php
@@ -12,10 +12,7 @@
 
 final class ErrorLoggingMiddleware implements MiddlewareInterface
 {
-    /**
-     * @var LoggerInterface
-     */
-    private $logger;
+    private LoggerInterface $logger;
 
     public function __construct(LoggerInterface $logger)
     {
diff --git a/src/StatusCodeExtractionStrategy/ClassMap.php b/src/StatusCodeExtractionStrategy/ClassMap.php
index b750fa6..a5108d7 100644
--- a/src/StatusCodeExtractionStrategy/ClassMap.php
+++ b/src/StatusCodeExtractionStrategy/ClassMap.php
@@ -24,7 +24,7 @@ final class ClassMap implements StatusCodeExtractionStrategy
     /**
      * @var array<string, int>
      */
-    private $conversionMap;
+    private array $conversionMap;
 
     /**
      * @param array<string, int> $conversionMap
@@ -42,6 +42,8 @@ public function extractStatusCode(Throwable $error): int
             }
         }
 
-        return $error->getCode() ?: StatusCodeInterface::STATUS_INTERNAL_SERVER_ERROR;
+        $code = $error->getCode();
+
+        return $code !== 0 ? $code : StatusCodeInterface::STATUS_INTERNAL_SERVER_ERROR;
     }
 }
diff --git a/tests/ErrorConversionMiddlewareTest.php b/tests/ErrorConversionMiddlewareTest.php
index 0ebf151..d0ca5bf 100644
--- a/tests/ErrorConversionMiddlewareTest.php
+++ b/tests/ErrorConversionMiddlewareTest.php
@@ -4,6 +4,9 @@
 namespace Lcobucci\ErrorHandling\Tests;
 
 use Fig\Http\Message\StatusCodeInterface;
+use Laminas\Diactoros\Response;
+use Laminas\Diactoros\ResponseFactory;
+use Laminas\Diactoros\ServerRequest;
 use Lcobucci\ContentNegotiation\UnformattedResponse;
 use Lcobucci\ErrorHandling\DebugInfoStrategy;
 use Lcobucci\ErrorHandling\DebugInfoStrategy\NoDebugInfo;
@@ -16,9 +19,6 @@
 use Psr\Http\Server\RequestHandlerInterface;
 use RuntimeException;
 use Throwable;
-use Zend\Diactoros\Response;
-use Zend\Diactoros\ResponseFactory;
-use Zend\Diactoros\ServerRequest;
 
 /**
  * @coversDefaultClass \Lcobucci\ErrorHandling\ErrorConversionMiddleware
@@ -29,15 +29,8 @@
  */
 final class ErrorConversionMiddlewareTest extends TestCase
 {
-    /**
-     * @var ResponseFactory
-     */
-    private $responseFactory;
-
-    /**
-     * @var ClassMap
-     */
-    private $statusCodeExtractor;
+    private ResponseFactory $responseFactory;
+    private ClassMap $statusCodeExtractor;
 
     /**
      * @before
@@ -94,7 +87,7 @@ public function processShouldConvertTheExceptionIntoAnUnformattedResponseWithThe
     }
 
     /**
-     * @return array<string, array<Throwable|array<string, mixed>>>
+     * @return array<string, array<Throwable|int|array<string, mixed>>>
      */
     public function possibleConversions(): iterable
     {
diff --git a/tests/ErrorLoggingMiddlewareTest.php b/tests/ErrorLoggingMiddlewareTest.php
index 0a189f3..febd446 100644
--- a/tests/ErrorLoggingMiddlewareTest.php
+++ b/tests/ErrorLoggingMiddlewareTest.php
@@ -3,14 +3,14 @@
 
 namespace Lcobucci\ErrorHandling\Tests;
 
+use Laminas\Diactoros\Response;
+use Laminas\Diactoros\ServerRequest;
 use Lcobucci\ErrorHandling\ErrorLoggingMiddleware;
 use PHPUnit\Framework\MockObject\MockObject;
 use PHPUnit\Framework\TestCase;
 use Psr\Http\Server\RequestHandlerInterface;
 use Psr\Log\LoggerInterface;
 use RuntimeException;
-use Zend\Diactoros\Response;
-use Zend\Diactoros\ServerRequest;
 
 /**
  * @coversDefaultClass \Lcobucci\ErrorHandling\ErrorLoggingMiddleware
@@ -20,7 +20,7 @@ final class ErrorLoggingMiddlewareTest extends TestCase
     /**
      * @var LoggerInterface&MockObject
      */
-    private $logger;
+    private LoggerInterface $logger;
 
     /**
      * @before