diff --git a/.docker/Dockerfile b/.docker/Dockerfile
index 2fd73ad..115a506 100644
--- a/.docker/Dockerfile
+++ b/.docker/Dockerfile
@@ -1,6 +1,5 @@
-ARG BASE_IMAGE=php:8.1-cli-alpine3.14
+ARG BASE_IMAGE=php:8.1-cli-alpine
 FROM ${BASE_IMAGE}
 
 RUN php -r "readfile('http://getcomposer.org/installer');" | php -- --install-dir=/usr/bin/ --filename=composer
-RUN apk add --no-cache python3 \
-  && ln -s /usr/bin/python3 /usr/bin/python
+RUN apk add --no-cache python3
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e0ecfcc..4038ef8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,6 +16,7 @@ jobs:
           - { php: 8.1, dependencies: "highest" }
           - { php: 8.2, dependencies: "highest" }
           - { php: 8.3, dependencies: "highest" }
+          - { php: 8.4, dependencies: "highest" }
     steps:
       - name: Checkout
         uses: actions/checkout@v2
@@ -39,8 +40,10 @@ jobs:
           - { phpunit: 10, php: 8.1 }
           - { phpunit: 10, php: 8.2 }
           - { phpunit: 10, php: 8.3 }
+          - { phpunit: 10, php: 8.4 }
           - { phpunit: 11, php: 8.2 }
           - { phpunit: 11, php: 8.3 }
+          - { phpunit: 11, php: 8.4 }
     steps:
       - name: Checkout
         uses: actions/checkout@v2
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3c0c6aa..51c0e0b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,7 +6,7 @@ The project follows [semantic versioning](http://semver.org/). `BC` stands for a
 
 ## [Unreleased]
 ### Added
-* Support for PHP 8.2
+* Support for PHP 8.2, 8.3, 8.4
 ### Removed
 * Support for PHP < 8.1
 * Support for PHPUnit < 10
diff --git a/Makefile b/Makefile
index 8a68b93..50e3a74 100644
--- a/Makefile
+++ b/Makefile
@@ -1,7 +1,15 @@
 .PHONY: run-php-8.1
 run-php-8.1:
-	docker-compose run php-8.1 sh
+	docker compose run php-8.1 sh
 
 .PHONY: run-php-8.2
 run-php-8.2:
-	docker-compose run php-8.2 sh
+	docker compose run php-8.2 sh
+
+.PHONY: run-php-8.3
+run-php-8.3:
+	docker compose run php-8.3 sh
+
+.PHONY: run-php-8.4
+run-php-8.4:
+	docker compose run php-8.4 sh
diff --git a/README.md b/README.md
index fa579b7..773a00b 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ In property-based testing, several properties that the System Under Test must re
 
 ## Compatibility
 
-- PHP 8.1, 8.2, 8.3
+- PHP 8.1, 8.2, 8.3, 8.4
 - PHPUnit 10.x, 11.x
 
 ## Installation
diff --git a/docker-compose.yml b/docker-compose.yml
index 5affdb1..1975ad6 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -9,7 +9,7 @@ services:
     build:
       context: .docker
       args:
-        BASE_IMAGE: php:8.1-cli-alpine3.14
+        BASE_IMAGE: php:8.1-cli-alpine
     volumes:
       - .:/usr/src/eris
     user: 1000:1000
@@ -18,7 +18,25 @@ services:
     build:
       context: .docker
       args:
-        BASE_IMAGE: php:8.2-cli-alpine3.16
+        BASE_IMAGE: php:8.2-cli-alpine
+    volumes:
+      - .:/usr/src/eris
+    user: 1000:1000
+    working_dir: /usr/src/eris
+  php-8.3:
+    build:
+      context: .docker
+      args:
+        BASE_IMAGE: php:8.3-cli-alpine
+    volumes:
+      - .:/usr/src/eris
+    user: 1000:1000
+    working_dir: /usr/src/eris
+  php-8.4:
+    build:
+      context: .docker
+      args:
+        BASE_IMAGE: php:8.4-cli-alpine
     volumes:
       - .:/usr/src/eris
     user: 1000:1000
diff --git a/src/Generator/IntegerGenerator.php b/src/Generator/IntegerGenerator.php
index 8a50fad..2083372 100644
--- a/src/Generator/IntegerGenerator.php
+++ b/src/Generator/IntegerGenerator.php
@@ -47,7 +47,7 @@ class IntegerGenerator implements Generator
 {
     private $mapFn;
 
-    public function __construct(callable $mapFn = null)
+    public function __construct(?callable $mapFn = null)
     {
         if (is_null($mapFn)) {
             $this->mapFn = $this->identity();
diff --git a/src/Listener.php b/src/Listener.php
index 380e3d7..e1dd451 100644
--- a/src/Listener.php
+++ b/src/Listener.php
@@ -18,7 +18,7 @@ public function startPropertyVerification();
      * @param null|Exception $exception  tells if the test has failed and specifies the exact exception
      * @return void
      */
-    public function endPropertyVerification($ordinaryEvaluations, $iterations, Exception $exception = null);
+    public function endPropertyVerification($ordinaryEvaluations, $iterations, ?Exception $exception = null);
 
     /**
      * @param array $generation  of mixed values
diff --git a/src/Listener/CollectFrequencies.php b/src/Listener/CollectFrequencies.php
index 25b63e8..8718429 100644
--- a/src/Listener/CollectFrequencies.php
+++ b/src/Listener/CollectFrequencies.php
@@ -9,7 +9,7 @@
 /**
  * @see Listeners::collectFrequencies()
  */
-function collectFrequencies(callable $collectFunction = null)
+function collectFrequencies(?callable $collectFunction = null)
 {
     return Listeners::collectFrequencies($collectFunction);
 }
@@ -40,7 +40,7 @@ public function __construct($collectFunction = null)
         $this->collectFunction = $collectFunction;
     }
 
-    public function endPropertyVerification($ordinaryEvaluations, $iterations, Exception $exception = null)
+    public function endPropertyVerification($ordinaryEvaluations, $iterations, ?Exception $exception = null)
     {
         arsort($this->collectedValues, SORT_NUMERIC);
         echo PHP_EOL;
diff --git a/src/Listener/EmptyListener.php b/src/Listener/EmptyListener.php
index 2cdbb29..d11afea 100644
--- a/src/Listener/EmptyListener.php
+++ b/src/Listener/EmptyListener.php
@@ -10,7 +10,7 @@ public function startPropertyVerification()
     {
     }
 
-    public function endPropertyVerification($ordinaryEvaluations, $iterations, Exception $exception = null)
+    public function endPropertyVerification($ordinaryEvaluations, $iterations, ?Exception $exception = null)
     {
     }
 
diff --git a/src/Listener/Log.php b/src/Listener/Log.php
index 4d846b5..c11325b 100644
--- a/src/Listener/Log.php
+++ b/src/Listener/Log.php
@@ -40,7 +40,7 @@ public function newGeneration(array $generation, $iteration)
         ));
     }
 
-    public function endPropertyVerification($ordinaryEvaluations, $iterations, Exception $exception = null)
+    public function endPropertyVerification($ordinaryEvaluations, $iterations, ?Exception $exception = null)
     {
         fclose($this->fp);
     }
diff --git a/src/Listener/MinimumEvaluations.php b/src/Listener/MinimumEvaluations.php
index e8bbe46..8e09872 100644
--- a/src/Listener/MinimumEvaluations.php
+++ b/src/Listener/MinimumEvaluations.php
@@ -23,7 +23,7 @@ private function __construct($threshold)
         $this->threshold = $threshold;
     }
 
-    public function endPropertyVerification($ordinaryEvaluations, $iterations, Exception $exception = null)
+    public function endPropertyVerification($ordinaryEvaluations, $iterations, ?Exception $exception = null)
     {
         if ($exception) {
             return;
diff --git a/src/Listeners.php b/src/Listeners.php
index ca87a60..48872fc 100644
--- a/src/Listeners.php
+++ b/src/Listeners.php
@@ -7,7 +7,7 @@
 
 final class Listeners
 {
-    public static function collectFrequencies(callable $collectFunction = null)
+    public static function collectFrequencies(?callable $collectFunction = null)
     {
         return new CollectFrequencies($collectFunction);
     }
diff --git a/src/TestTrait.php b/src/TestTrait.php
index 7bfe58a..4bd2be6 100644
--- a/src/TestTrait.php
+++ b/src/TestTrait.php
@@ -57,13 +57,13 @@ public function getTestCaseAttributes()
         }
 
         $methodAttributes = [];
-        foreach($reflectionClass->getMethods() as $method) {
-            if($method->getName() !== $this->name()) {
+        foreach ($reflectionClass->getMethods() as $method) {
+            if ($method->getName() !== $this->name()) {
                 continue;
             }
             $attributes = $method->getAttributes();
 
-            if(!empty($attributes)) {
+            if (!empty($attributes)) {
                 foreach ($attributes as $attribute) {
                     $methodAttributes[$attribute->getName()] = ($attribute)->newInstance();
                 }