diff --git a/bin/composer.phar b/bin/composer.phar
index bd5bab8c..b58b584b 100755
Binary files a/bin/composer.phar and b/bin/composer.phar differ
diff --git a/bin/dphp b/bin/dphp
index 9d15ab52..4e04531d 100755
Binary files a/bin/dphp and b/bin/dphp differ
diff --git a/src/DurableFuture.php b/src/DurableFuture.php
index a77bfda4..206924d7 100644
--- a/src/DurableFuture.php
+++ b/src/DurableFuture.php
@@ -25,6 +25,8 @@
 namespace Bottledcode\DurablePhp;
 
 use Amp\DeferredFuture;
+use Bottledcode\DurablePhp\State\Serializer;
+use LogicException;
 
 /**
  * @template T
@@ -32,9 +34,10 @@
 class DurableFuture
 {
     /**
-     * @param DeferredFuture<T> $future
+     * @param  DeferredFuture<T>  $future
+     * @param  class-string<T>|null  $resultType
      */
-    public function __construct(public readonly DeferredFuture $future) {}
+    public function __construct(public readonly DeferredFuture $future, public readonly ?string $resultType = null) {}
 
     /**
      * @return T
@@ -42,10 +45,14 @@ public function __construct(public readonly DeferredFuture $future) {}
     public function getResult(): mixed
     {
         if ($this->future->isComplete()) {
-            return $this->future->getFuture()->await();
+            if ($this->resultType === null) {
+                return $this->future->getFuture()->await();
+            }
+
+            return Serializer::deserialize($this->future->getFuture()->await(), $this->resultType);
         }
 
-        throw new \LogicException('Future is not complete');
+        throw new LogicException('Future is not complete');
     }
 
     public function hasResult(): bool
diff --git a/src/OrchestrationContext.php b/src/OrchestrationContext.php
index 01019b0e..00b24c73 100644
--- a/src/OrchestrationContext.php
+++ b/src/OrchestrationContext.php
@@ -70,19 +70,18 @@ final class OrchestrationContext implements OrchestrationContextInterface
 
     private int $randomKey = 0;
 
-    public function callActivity(string $name, array $args = [], ?RetryOptions $retryOptions = null): DurableFuture
+    public function callActivity(string $name, ?string $returnType = null, ?RetryOptions $retryOptions = null, mixed ...$args): DurableFuture
     {
         $this->durableLogger->debug('Calling activity', ['name' => $name]);
         $identity = $this->newGuid();
 
         return $this->createFuture(
-            fn()
-                => $this->taskController->fire(
-                    AwaitResult::forEvent(
-                        StateId::fromInstance($this->id),
-                        WithActivity::forEvent($identity, ScheduleTask::forName($name, $args)),
-                    ),
+            fn() => $this->taskController->fire(
+                AwaitResult::forEvent(
+                    StateId::fromInstance($this->id),
+                    WithActivity::forEvent($identity, ScheduleTask::forName($name, $args)),
                 ),
+            ),
             function (Event $event, string $eventIdentity) use ($identity): array {
                 if (($event instanceof TaskCompleted || $event instanceof TaskFailed) &&
                     $eventIdentity === $identity->toString()) {
@@ -92,6 +91,7 @@ function (Event $event, string $eventIdentity) use ($identity): array {
                 return [null, false];
             },
             $identity->toString(),
+            $returnType,
         );
     }
 
@@ -113,9 +113,10 @@ private function createFuture(
         Closure $onSent,
         Closure $onReceived,
         ?string $identity = null,
+        ?string $resultType = null,
     ): DurableFuture {
         $identity ??= $this->history->historicalTaskResults->getIdentity();
-        if (!$this->history->historicalTaskResults->hasSentIdentity($identity)) {
+        if (! $this->history->historicalTaskResults->hasSentIdentity($identity)) {
             $this->durableLogger->debug('Future requested for an unsent identity', [$identity]);
             [$eventId] = $onSent();
             $deferred = new DeferredFuture();
@@ -129,7 +130,7 @@ private function createFuture(
         $this->durableLogger->debug('Future requested for a sent identity, processing future', [$identity]);
 
         $deferred = new DeferredFuture();
-        $future = new DurableFuture($deferred);
+        $future = new DurableFuture($deferred, $resultType);
         $this->history->historicalTaskResults->trackFuture($onReceived, $future);
 
         return $future;
@@ -177,9 +178,9 @@ public function callActivityInline(Closure $activity): DurableFuture
 
     public function callSubOrchestrator(
         string $name,
-        array $args = [],
         ?string $instanceId = null,
         ?RetryOptions $retryOptions = null,
+        mixed ...$args,
     ): DurableFuture {
         throw new LogicException('Not implemented');
     }
@@ -214,13 +215,12 @@ public function createTimer(DateTimeImmutable|DateInterval $fireAt): DurableFutu
         $identity = sha1($fireAt->format('c'));
 
         return $this->createFuture(
-            fn()
-                => $this->taskController->fire(
-                    WithOrchestration::forInstance(
-                        StateId::fromInstance($this->id),
-                        WithDelay::forEvent($fireAt, RaiseEvent::forTimer($identity)),
-                    ),
+            fn() => $this->taskController->fire(
+                WithOrchestration::forInstance(
+                    StateId::fromInstance($this->id),
+                    WithDelay::forEvent($fireAt, RaiseEvent::forTimer($identity)),
                 ),
+            ),
             function (Event $event) use ($identity): array {
                 if ($event instanceof RaiseEvent && $event->eventName === $identity) {
                     return [$event, true];
@@ -236,10 +236,10 @@ public function getCurrentTime(): DateTimeImmutable
         return $this->history->historicalTaskResults->getCurrentTime();
     }
 
-    public function waitForExternalEvent(string $name): DurableFuture
+    public function waitForExternalEvent(string $name, ?string $resultType = null): DurableFuture
     {
         $this->durableLogger->debug('Waiting for external event', ['name' => $name]);
-        $future = new DurableFuture(new DeferredFuture());
+        $future = new DurableFuture(new DeferredFuture(), $resultType);
         $this->history->historicalTaskResults->trackFuture(function (Event $event) use ($name): array {
             $found = false;
             $result = null;
@@ -370,7 +370,7 @@ public function isLockedOwned(EntityId $entityId): bool
     public function lockEntity(EntityId ...$entityId): EntityLock
     {
         $this->durableLogger->debug('Locking entities', ['entityId' => $entityId]);
-        if (!empty($this->history->locks ?? []) && !$this->isReplaying()) {
+        if (! empty($this->history->locks ?? []) && ! $this->isReplaying()) {
             throw new LogicException('Cannot lock an entity while holding locks');
         }
 
@@ -447,7 +447,7 @@ public function waitAll(DurableFuture ...$tasks): array
     /**
      * @template T
      *
-     * @param class-string<T> $className
+     * @param  class-string<T>  $className
      * @return T
      */
     public function createEntityProxy(string $className, ?EntityId $entityId = null): object
@@ -457,7 +457,7 @@ public function createEntityProxy(string $className, ?EntityId $entityId = null)
         }
 
         $class = new ReflectionClass($className);
-        if (!$class->isInterface()) {
+        if (! $class->isInterface()) {
             throw new LogicException('Only interfaces can be proxied');
         }
 
@@ -577,7 +577,7 @@ public function entityOp(string|EntityId $id, Closure $operation): mixed
         }
 
         $name = $type->getName();
-        if (!interface_exists($name)) {
+        if (! interface_exists($name)) {
             throw new LogicException('Unable to load interface: ' . $name);
         }
 
diff --git a/src/OrchestrationContextInterface.php b/src/OrchestrationContextInterface.php
index 52afe692..5f7d4f91 100644
--- a/src/OrchestrationContextInterface.php
+++ b/src/OrchestrationContextInterface.php
@@ -41,11 +41,12 @@ interface OrchestrationContextInterface
      * @template T
      *
      * @param  string  $name  The name of the function to remotely invoke
-     * @param  array  $args  The arguments to pass to the function
+     * @param  class-string<T>|null  $returnType
      * @param  RetryOptions|null  $retryOptions  How to retry on failure
+     * @param  array  $args  The arguments to pass to the function
      * @return DurableFuture<T>
      */
-    public function callActivity(string $name, array $args = [], ?RetryOptions $retryOptions = null): DurableFuture;
+    public function callActivity(string $name, ?string $returnType = null, ?RetryOptions $retryOptions = null, mixed ...$args): DurableFuture;
 
     /**
      * Calls an activity inline. There are no retries and exceptions will cause an immediate failure.
@@ -94,9 +95,9 @@ public function lockEntity(EntityId ...$entityId): EntityLock;
 
     public function callSubOrchestrator(
         string $name,
-        array $args = [],
         ?string $instanceId = null,
         ?RetryOptions $retryOptions = null,
+        mixed ...$args,
     ): DurableFuture;
 
     public function continueAsNew(array $args = []): never;
@@ -133,9 +134,10 @@ public function setCustomStatus(string $customStatus): void;
      *
      * @template T
      *
+     * @param  class-string<T>|null  $resultType
      * @return DurableFuture<T>
      */
-    public function waitForExternalEvent(string $name): DurableFuture;
+    public function waitForExternalEvent(string $name, ?string $resultType = null): DurableFuture;
 
     /**
      * Gets the current time in a deterministic way. (always the time the execution started)
@@ -190,11 +192,20 @@ public function waitAny(DurableFuture ...$tasks): DurableFuture;
 
     /**
      * Returns once all futures have completed.
+     *
+     * @template-covariant T
+     *
+     * @return array<T>
      */
     public function waitAll(DurableFuture ...$tasks): array;
 
     /**
      * Returns the result (or throws on failure) once a single future has completed.
+     *
+     * @template T
+     *
+     * @param  DurableFuture<T>  $task
+     * @return T
      */
     public function waitOne(DurableFuture $task): mixed;
 
diff --git a/src/RemoteOrchestrationClient.php b/src/RemoteOrchestrationClient.php
index 1be81766..39b2d592 100644
--- a/src/RemoteOrchestrationClient.php
+++ b/src/RemoteOrchestrationClient.php
@@ -35,7 +35,9 @@
 use Bottledcode\DurablePhp\State\Status;
 use Exception;
 use Generator;
+use JsonException;
 use Override;
+use RuntimeException;
 use Withinboredom\Time\Unit;
 
 use function Withinboredom\Time\Hours;
@@ -94,7 +96,11 @@ public function getStatus(OrchestrationInstance $instance): Status
         while ($result->getBody()->isReadable()) {
             $body .= $result->getBody()->buffer();
         }
-        $result = json_decode($body, true, 512, JSON_THROW_ON_ERROR);
+        try {
+            $result = json_decode($body, true, flags: JSON_THROW_ON_ERROR);
+        } catch (JsonException $exception) {
+            throw new RuntimeException('Failed to decode JSON: ' . $body, previous: $exception);
+        }
 
         return Serializer::deserialize($result, Status::class);
     }
diff --git a/src/Testing/DummyOrchestrationContext.php b/src/Testing/DummyOrchestrationContext.php
index 9b4453e2..e62a9b62 100644
--- a/src/Testing/DummyOrchestrationContext.php
+++ b/src/Testing/DummyOrchestrationContext.php
@@ -106,8 +106,9 @@ public function asUser(string $userId): void
 
     public function callActivity(
         string $name,
-        array $args = [],
+        ?string $returnType = null,
         ?RetryOptions $retryOptions = null,
+        mixed ...$args,
     ): DurableFuture {
         $future = new DeferredFuture();
         if ($this->activities[$name] ?? false) {
@@ -118,7 +119,7 @@ public function callActivity(
                 $future->complete($result);
             }
 
-            return new DurableFuture($future);
+            return new DurableFuture($future, $returnType);
         }
 
         throw new LogicException('Failed to find registered activity: ' . $name);
@@ -147,7 +148,7 @@ public function entityOp(EntityId|string $id, Closure $operation): mixed
         }
 
         $name = $type->getName();
-        if (!interface_exists($name)) {
+        if (! interface_exists($name)) {
             throw new LogicException('Unable to load interface: ' . $name);
         }
 
@@ -230,9 +231,9 @@ public function lockEntity(EntityId ...$entityId): EntityLock
 
     public function callSubOrchestrator(
         string $name,
-        array $args = [],
         ?string $instanceId = null,
         ?RetryOptions $retryOptions = null,
+        mixed ...$args,
     ): DurableFuture {
         throw new LogicException('Not implemented');
     }
@@ -260,13 +261,13 @@ public function setCustomStatus(string $customStatus): void
         $this->status = $this->status->with(customStatus: $customStatus);
     }
 
-    public function waitForExternalEvent(string $name): DurableFuture
+    public function waitForExternalEvent(string $name, ?string $resultType = null): DurableFuture
     {
         $future = new DeferredFuture();
         $value = $this->events[$name] ?? throw new LogicException('Event not found: ' . $name);
         $future->complete($value);
 
-        return new DurableFuture($future);
+        return new DurableFuture($future, $resultType);
     }
 
     public function getCurrentTime(): DateTimeImmutable
@@ -358,7 +359,7 @@ public function waitAll(DurableFuture ...$tasks): array
     {
         $results = [];
         foreach ($tasks as $task) {
-            if (!$task->future->isComplete()) {
+            if (! $task->future->isComplete()) {
                 throw new LogicException('Not all futures are completed');
             }
             $results[] = $task->getResult();
@@ -376,7 +377,7 @@ public function createEntityProxy(
         }
 
         $class = new ReflectionClass($className);
-        if (!$class->isInterface()) {
+        if (! $class->isInterface()) {
             throw new LogicException('Only interfaces can be proxied');
         }
 
diff --git a/tests/PerformanceTests/Dockerfile b/tests/PerformanceTests/Dockerfile
index 1fe18aab..3e6396c0 100644
--- a/tests/PerformanceTests/Dockerfile
+++ b/tests/PerformanceTests/Dockerfile
@@ -1,4 +1,4 @@
-FROM php:8.3-zts
+FROM php:8.4-zts
 
 COPY --from=mlocati/php-extension-installer /usr/bin/install-php-extensions /usr/local/bin/
 
diff --git a/tests/PerformanceTests/FanOutFanIn.php b/tests/PerformanceTests/FanOutFanIn.php
index 3565d185..74fed973 100644
--- a/tests/PerformanceTests/FanOutFanIn.php
+++ b/tests/PerformanceTests/FanOutFanIn.php
@@ -1,4 +1,5 @@
 <?php
+
 /*
  * Copyright ©2024 Robert Landers
  *
@@ -35,7 +36,7 @@ public function __invoke(OrchestrationContextInterface $context): void
         $count = $context->getInput()['count'];
         $tasks = [];
         for ($i = 0; $i < $count; $i++) {
-            $tasks[] = $context->callActivity(SayHello::class, [mb_str_pad((string) $i, 4, '0', STR_PAD_LEFT)]);
+            $tasks[] = $context->callActivity(SayHello::class, null, null, mb_str_pad((string) $i, 4, '0', STR_PAD_LEFT));
         }
         $context->waitAll(...$tasks);
         foreach ($tasks as $i => $task) {
diff --git a/tests/PerformanceTests/HelloCities/HelloSequence.php b/tests/PerformanceTests/HelloCities/HelloSequence.php
index 18195d78..0f4be682 100644
--- a/tests/PerformanceTests/HelloCities/HelloSequence.php
+++ b/tests/PerformanceTests/HelloCities/HelloSequence.php
@@ -1,4 +1,5 @@
 <?php
+
 /*
  * Copyright ©2024 Robert Landers
  *
@@ -33,11 +34,11 @@ class HelloSequence
     public function __invoke(OrchestrationContextInterface $context): array
     {
         $outputs = [
-            $context->callActivity(SayHello::class, ['Tokyo']),
-            $context->callActivity(SayHello::class, ['Seattle']),
-            $context->callActivity(SayHello::class, ['London']),
-            $context->callActivity(SayHello::class, ['Amsterdam']),
-            $context->callActivity(SayHello::class, ['Seoul']),
+            $context->callActivity(SayHello::class, null, null, 'Tokyo'),
+            $context->callActivity(SayHello::class, null, null, 'Seattle'),
+            $context->callActivity(SayHello::class, null, null, 'London'),
+            $context->callActivity(SayHello::class, null, null, 'Amsterdam'),
+            $context->callActivity(SayHello::class, null, null, 'Seoul'),
         ];
 
         return $context->waitAll(...$outputs);
diff --git a/tests/PerformanceTests/Sequence.php b/tests/PerformanceTests/Sequence.php
index b3555a76..738a2236 100644
--- a/tests/PerformanceTests/Sequence.php
+++ b/tests/PerformanceTests/Sequence.php
@@ -1,4 +1,5 @@
 <?php
+
 /*
  * Copyright ©2024 Robert Landers
  *
@@ -35,7 +36,7 @@ public function __invoke(OrchestrationContextInterface $context)
         $sequence = $context->getInput();
         $results = [];
         foreach ($sequence as $value) {
-            $results[] = $context->waitOne($context->callActivity(SayHello::class, ['name' => $value]));
+            $results[] = $context->waitOne($context->callActivity(SayHello::class, null, null, $value));
         }
 
         return $results;
diff --git a/tests/Unit/OrchestrationHistoryTest.php b/tests/Unit/OrchestrationHistoryTest.php
index 93e9e1f9..68a490f8 100644
--- a/tests/Unit/OrchestrationHistoryTest.php
+++ b/tests/Unit/OrchestrationHistoryTest.php
@@ -196,7 +196,7 @@ public function entry(string $test, SerializedType $type): string
 it('can call an activity with a successful result', function (): void {
     $instance = getOrchestration(
         'test',
-        fn(OrchestrationContext $context) => $context->waitOne($context->callActivity('test', ['hello world'])),
+        fn(OrchestrationContext $context) => $context->waitOne($context->callActivity('test', null, null, args: 'hello world')),
         [],
         $nextEvent,
     );
@@ -215,16 +215,14 @@ public function entry(string $test, SerializedType $type): string
 });
 
 it('can call an activity with a successful result (example)', function (): void {
-    $instance = fn(OrchestrationContextInterface $context)
-        => $context->waitOne($context->callActivity('test', ['hello world']));
+    $instance = fn(OrchestrationContextInterface $context) => $context->waitOne($context->callActivity('test', args: 'hello world'));
     $context = new DummyOrchestrationContext($instance, []);
     $context->handleActivities(new ActivityMock('test', 'pretty colors'));
     expect($instance($context))->toBe(['pretty colors']);
 });
 
 it('can call an activity with a failed result (example)', function (): void {
-    $instance = fn(OrchestrationContextInterface $context)
-        => $context->waitOne($context->callActivity('test', ['hello world']));
+    $instance = fn(OrchestrationContextInterface $context) => $context->waitOne($context->callActivity('test', args: 'hello world'));
     $context = new DummyOrchestrationContext($instance, []);
     $context->handleActivities(new ActivityMock('test', new Exception('hello world')));
     expect(fn() => $instance($context))->toThrow(Exception::class, 'hello world');
@@ -233,7 +231,7 @@ public function entry(string $test, SerializedType $type): string
 it('can call an activity with a failed result', function (): void {
     $instance = getOrchestration(
         'test',
-        fn(OrchestrationContext $context) => $context->waitOne($context->callActivity('test', ['hello world'])),
+        fn(OrchestrationContext $context) => $context->waitOne($context->callActivity('test', args: 'hello world')),
         [],
         $nextEvent,
     );