diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d57cdd0..cea168a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -8,13 +8,13 @@ on:
 jobs:
   test:
     name: test
-    runs-on: "ubuntu-latest"
+    runs-on: "ubuntu-24.04"
 
     strategy:
       matrix:
         include:
-          - php-version: 8.2
           - php-version: 8.3
+          - php-version: 8.4
 
 
     steps:
@@ -29,13 +29,13 @@ jobs:
 
   examples:
     name: examples
-    runs-on: "ubuntu-latest"
+    runs-on: "ubuntu-24.04"
 
     strategy:
       matrix:
         include:
-          - php-version: 8.2
           - php-version: 8.3
+          - php-version: 8.4
 
     steps:
       - name: checkout
diff --git a/composer.json b/composer.json
index 56827d8..66d3ddd 100644
--- a/composer.json
+++ b/composer.json
@@ -6,9 +6,9 @@
         { "name": "Christopher Davis", "email": "chris@pmg.com" }
     ],
     "require": {
-        "php": "^8.2",
+        "php": "^8.3",
         "psr/log": "^1.0 || ^2.0 || ^3.0",
-        "guzzlehttp/promises": "^1.3"
+        "guzzlehttp/promises": "^2.0.3"
 
     },
     "require-dev": {
diff --git a/src/AbstractConsumer.php b/src/AbstractConsumer.php
index 9a14a29..762b55f 100644
--- a/src/AbstractConsumer.php
+++ b/src/AbstractConsumer.php
@@ -46,7 +46,7 @@ abstract class AbstractConsumer implements Consumer
      */
     private $hasPcntl = null;
 
-    public function __construct(LoggerInterface $logger=null)
+    public function __construct(?LoggerInterface $logger=null)
     {
         $this->logger = $logger;
     }
@@ -54,7 +54,7 @@ public function __construct(LoggerInterface $logger=null)
     /**
      * {@inheritdoc}
      */
-    public function run(string $queueName, MessageLifecycle $lifecycle=null) : int
+    public function run(string $queueName, ?MessageLifecycle $lifecycle=null) : int
     {
         $lifecycle = $lifecycle ?? new Lifecycle\NullLifecycle();
         $this->running = true;
@@ -81,7 +81,7 @@ public function run(string $queueName, MessageLifecycle $lifecycle=null) : int
     /**
      * {@inheritdoc}
      */
-    public function stop(int $code=null) : void
+    public function stop(?int $code=null) : void
     {
         $this->running = false;
         $this->exitCode = null === $code ? self::EXIT_SUCCESS : $code;
diff --git a/src/Consumer.php b/src/Consumer.php
index aded841..24d9653 100644
--- a/src/Consumer.php
+++ b/src/Consumer.php
@@ -31,7 +31,7 @@ interface Consumer
      * @param $lifecycle The message lifecycle to apply to the running consumer.
      * @return int The exit code to be used for the consumer.
      */
-    public function run(string $queueName, MessageLifecycle $lifecycle=null) : int;
+    public function run(string $queueName, ?MessageLifecycle $lifecycle=null) : int;
 
     /**
      * Consume a single job from the given queue. This will block until the
@@ -47,7 +47,7 @@ public function run(string $queueName, MessageLifecycle $lifecycle=null) : int;
      * @return  boolean|null True if the a job was execute successfully. Null if
      *          no job was executed. See the logs.
      */
-    public function once(string $queueName, MessageLifecycle $lifecycle=null) : ?bool;
+    public function once(string $queueName, ?MessageLifecycle $lifecycle=null) : ?bool;
 
     /**
      * Gracefully stop the consumer with the given exit code.
@@ -55,5 +55,5 @@ public function once(string $queueName, MessageLifecycle $lifecycle=null) : ?boo
      * @param int $code The exit code passed to `exit`. If null `EXIT_SUCCESS` is used.
      * @return void
      */
-    public function stop(int $code=null) : void;
+    public function stop(?int $code=null) : void;
 }
diff --git a/src/DefaultConsumer.php b/src/DefaultConsumer.php
index f09727e..2a12376 100644
--- a/src/DefaultConsumer.php
+++ b/src/DefaultConsumer.php
@@ -54,8 +54,8 @@ class DefaultConsumer extends AbstractConsumer
     public function __construct(
         Driver $driver,
         MessageHandler $handler,
-        RetrySpec $retries=null,
-        LoggerInterface $logger=null
+        ?RetrySpec $retries=null,
+        ?LoggerInterface $logger=null
     ) {
         parent::__construct($logger);
         $this->driver = $driver;
@@ -66,7 +66,7 @@ public function __construct(
     /**
      * {@inheritdoc}
      */
-    public function once(string $queueName, MessageLifecycle $lifecycle=null) : ?bool
+    public function once(string $queueName, ?MessageLifecycle $lifecycle=null) : ?bool
     {
         $envelope = $this->driver->dequeue($queueName);
         if (!$envelope) {
@@ -96,7 +96,7 @@ public function once(string $queueName, MessageLifecycle $lifecycle=null) : ?boo
     /**
      * {@inheritdoc}
      */
-    public function stop(int $code=null) : void
+    public function stop(?int $code=null) : void
     {
         if ($this->currentPromise) {
             $this->currentPromise->cancel();
diff --git a/src/Handler/PcntlForkingHandler.php b/src/Handler/PcntlForkingHandler.php
index 8581be7..ad60ddd 100644
--- a/src/Handler/PcntlForkingHandler.php
+++ b/src/Handler/PcntlForkingHandler.php
@@ -39,7 +39,7 @@ final class PcntlForkingHandler implements MessageHandler
 
     private Pcntl $pcntl;
 
-    public function __construct(MessageHandler $wrapped, Pcntl $pcntl=null)
+    public function __construct(MessageHandler $wrapped, ?Pcntl $pcntl=null)
     {
         $this->wrapped = $wrapped;
         $this->pcntl = $pcntl ?: new Pcntl();
diff --git a/src/Lifecycle/MappingLifecycle.php b/src/Lifecycle/MappingLifecycle.php
index e8aae43..c0e8e59 100644
--- a/src/Lifecycle/MappingLifecycle.php
+++ b/src/Lifecycle/MappingLifecycle.php
@@ -45,7 +45,7 @@ final class MappingLifecycle implements MessageLifecycle
      * @param $fallback The message lifecycle to which unmatches messages will be applied
      * @throws InvalidArgumentException if $mapping is a bad type
      */
-    public function __construct($mapping, MessageLifecycle $fallback=null)
+    public function __construct($mapping, ?MessageLifecycle $fallback=null)
     {
         if (!is_array($mapping) && !$mapping instanceof \ArrayAccess) {
             throw new InvalidArgumentException(sprintf(
diff --git a/src/Retry/LimitedSpec.php b/src/Retry/LimitedSpec.php
index c129123..31e58d8 100644
--- a/src/Retry/LimitedSpec.php
+++ b/src/Retry/LimitedSpec.php
@@ -29,7 +29,7 @@ final class LimitedSpec implements RetrySpec
     private $maxAttempts;
     private $retryDelay;
 
-    public function __construct(int $maxAttempts=null, int $retryDelay=0)
+    public function __construct(?int $maxAttempts=null, int $retryDelay=0)
     {
         if (null !== $maxAttempts && $maxAttempts < 1) {
             throw new InvalidArgumentException(sprintf(
diff --git a/src/Serializer/NativeSerializer.php b/src/Serializer/NativeSerializer.php
index 95b4ca7..1502bc6 100644
--- a/src/Serializer/NativeSerializer.php
+++ b/src/Serializer/NativeSerializer.php
@@ -41,13 +41,13 @@ final class NativeSerializer implements Serializer
      */
     private $signer;
 
-    public function __construct(Signer $signer, array $allowedClasses=null)
+    public function __construct(Signer $signer, ?array $allowedClasses=null)
     {
         $this->signer = $signer;
         $this->allowedClasses = $allowedClasses;
     }
 
-    public static function fromSigningKey(string $key, array $allowedClasses=null)
+    public static function fromSigningKey(string $key, ?array $allowedClasses=null)
     {
         return new self(new HmacSha256($key), $allowedClasses);
     }
diff --git a/test/unit/Driver/AbstractPersistanceDriverTest.php b/test/unit/Driver/AbstractPersistanceDriverTest.php
index f6a07e3..9603e54 100644
--- a/test/unit/Driver/AbstractPersistanceDriverTest.php
+++ b/test/unit/Driver/AbstractPersistanceDriverTest.php
@@ -24,7 +24,7 @@
 // not called
 abstract class _DriverAbc extends AbstractPersistanceDriver
 {
-    public function __construct(Serializer $serializer=null)
+    public function __construct(?Serializer $serializer=null)
     {
         if ($serializer) {
             parent::__construct($serializer);
diff --git a/test/unit/Handler/PcntlForkingHandlerTest.php b/test/unit/Handler/PcntlForkingHandlerTest.php
index 5a9f391..97779b4 100644
--- a/test/unit/Handler/PcntlForkingHandlerTest.php
+++ b/test/unit/Handler/PcntlForkingHandlerTest.php
@@ -160,7 +160,7 @@ protected function setUp() : void
         $this->message = new SimpleMessage(self::NAME);
     }
 
-    private function createHandler(callable $callback, Pcntl $pcntl=null)
+    private function createHandler(callable $callback, ?Pcntl $pcntl=null)
     {
         return new PcntlForkingHandler(new CallableHandler($callback), $pcntl);
     }