diff --git a/docs/component/async.md b/docs/component/async.md
index ff691210..593f4d6c 100644
--- a/docs/component/async.md
+++ b/docs/component/async.md
@@ -12,7 +12,7 @@
 
 #### `Functions`
 
-- [all](./../../src/Psl/Async/all.php#L17)
+- [all](./../../src/Psl/Async/all.php#L23)
 - [any](./../../src/Psl/Async/any.php#L25)
 - [await](./../../src/Psl/Async/await.php#L18)
 - [await_readable](./../../src/Psl/Async/await_readable.php#L18)
@@ -21,7 +21,7 @@
 - [concurrently](./../../src/Psl/Async/concurrently.php#L19)
 - [first](./../../src/Psl/Async/first.php#L24)
 - [later](./../../src/Psl/Async/later.php#L14)
-- [run](./../../src/Psl/Async/run.php#L19)
+- [run](./../../src/Psl/Async/run.php#L20)
 - [usleep](./../../src/Psl/Async/usleep.php#L10)
 
 #### `Classes`
diff --git a/src/Psl/Async/all.php b/src/Psl/Async/all.php
index 8d74e3be..00055493 100644
--- a/src/Psl/Async/all.php
+++ b/src/Psl/Async/all.php
@@ -4,8 +4,14 @@
 
 namespace Psl\Async;
 
+use Throwable;
+
 /**
- * Awaits all awaitables to complete or aborts if any errors concurrently.
+ * Awaits all awaitables to complete concurrently.
+ *
+ * If one or more awaitables fail, the first exception will be thrown.
+ *
+ * This function will wait for all awaitables to finish, even if the first one fails.
  *
  * @template Tk of array-key
  * @template Tv
@@ -17,10 +23,20 @@
 function all(iterable $awaitables): array
 {
     $values = [];
+    $errors = [];
 
     // Awaitable::iterate() to throw the first error based on completion order instead of argument order
     foreach (Awaitable::iterate($awaitables) as $index => $awaitable) {
-        $values[$index] = $awaitable->await();
+        try {
+            $values[$index] = $awaitable->await();
+        } catch (Throwable $throwable) {
+            $errors[] = $throwable;
+        }
+    }
+
+    if ($errors !== []) {
+        /** @psalm-suppress MissingThrowsDocblock */
+        throw $errors[0];
     }
 
     return $values;
diff --git a/src/Psl/Async/await_readable.php b/src/Psl/Async/await_readable.php
index 7457ea81..5e11d164 100644
--- a/src/Psl/Async/await_readable.php
+++ b/src/Psl/Async/await_readable.php
@@ -27,13 +27,7 @@ function await_readable(mixed $resource, bool $reference = true, ?int $timeout_m
 
     $watcher = EventLoop::onReadable(
         $resource,
-        static function (string $_watcher, mixed $resource) use ($suspension, $timeout_watcher): void {
-            if (null !== $timeout_watcher) {
-                Scheduler::cancel($timeout_watcher);
-            }
-
-            $suspension->resume($resource);
-        },
+        static fn() => $suspension->resume($resource),
     );
 
     if (!$reference) {
@@ -44,5 +38,10 @@ static function (string $_watcher, mixed $resource) use ($suspension, $timeout_w
         $suspension->suspend();
     } finally {
         Scheduler::cancel($watcher);
+
+        // cancel timeout watcher
+        if (null !== $timeout_watcher) {
+            Scheduler::cancel($timeout_watcher);
+        }
     }
 }
diff --git a/src/Psl/Async/await_signal.php b/src/Psl/Async/await_signal.php
index 6a0a2381..9c85a67f 100644
--- a/src/Psl/Async/await_signal.php
+++ b/src/Psl/Async/await_signal.php
@@ -27,13 +27,7 @@ function await_signal(int $signal, bool $reference = true, ?int $timeout_ms = nu
 
     $watcher = EventLoop::onSignal(
         $signal,
-        static function (string $_watcher, int $signal) use ($suspension, $timeout_watcher): void {
-            if (null !== $timeout_watcher) {
-                Scheduler::cancel($timeout_watcher);
-            }
-
-            $suspension->resume($signal);
-        },
+        static fn() => $suspension->resume($signal),
     );
 
     if (!$reference) {
@@ -44,5 +38,10 @@ static function (string $_watcher, int $signal) use ($suspension, $timeout_watch
         $suspension->suspend();
     } finally {
         Scheduler::cancel($watcher);
+
+        // cancel timeout watcher
+        if (null !== $timeout_watcher) {
+            Scheduler::cancel($timeout_watcher);
+        }
     }
 }
diff --git a/src/Psl/Async/await_writable.php b/src/Psl/Async/await_writable.php
index 46622f82..b5e3bd2d 100644
--- a/src/Psl/Async/await_writable.php
+++ b/src/Psl/Async/await_writable.php
@@ -27,23 +27,21 @@ function await_writable(mixed $resource, bool $reference = true, ?int $timeout_m
 
     $watcher = EventLoop::onWritable(
         $resource,
-        static function (string $_watcher, mixed $resource) use ($suspension, $timeout_watcher): void {
-            if (null !== $timeout_watcher) {
-                Scheduler::cancel($timeout_watcher);
-            }
-
-            $suspension->resume($resource);
-        },
+        static fn() => $suspension->resume($resource),
     );
 
     if (!$reference) {
         Scheduler::unreference($watcher);
     }
 
-
     try {
         $suspension->suspend();
     } finally {
         Scheduler::cancel($watcher);
+
+        // cancel timeout watcher
+        if (null !== $timeout_watcher) {
+            Scheduler::cancel($timeout_watcher);
+        }
     }
 }
diff --git a/src/Psl/Async/run.php b/src/Psl/Async/run.php
index 8c3b354a..04b27113 100644
--- a/src/Psl/Async/run.php
+++ b/src/Psl/Async/run.php
@@ -4,6 +4,7 @@
 
 namespace Psl\Async;
 
+use Psl;
 use Psl\Async\Exception\TimeoutException;
 use Throwable;
 
@@ -20,33 +21,50 @@ function run(callable $callable, ?int $timeout_ms = null): Awaitable
 {
     $state = new Internal\State();
 
-    $timeout_watcher = null;
+    /** @var Psl\Ref<string|null> $timeout_watcher */
+    $timeout_watcher = new Psl\Ref(null);
+    /** @var Psl\Ref<string|null> $delay_watcher */
+    $delay_watcher = new Psl\Ref(null);
+
     if (null !== $timeout_ms) {
-        $timeout_watcher = Scheduler::delay($timeout_ms, static function () use ($state): void {
+        $timeout_watcher->value = Scheduler::delay($timeout_ms, static function () use ($state, $delay_watcher, $timeout_watcher): void {
+            if (null !== $delay_watcher->value) {
+                $delay_watcher_value = $delay_watcher->value;
+                $delay_watcher->value = null;
+                Scheduler::cancel($delay_watcher_value);
+            }
+
+            $timeout_watcher->value = null;
             $state->error(new TimeoutException());
         });
 
-        Scheduler::unreference($timeout_watcher);
+        Scheduler::unreference($timeout_watcher->value);
     }
 
-    Scheduler::defer(static function () use ($callable, $state, $timeout_watcher): void {
+    $delay_watcher->value = Scheduler::defer(static function () use ($callable, $state, $timeout_watcher): void {
+        $exception = null;
+        $result = null;
         try {
             $result = $callable();
-            if (null !== $timeout_watcher) {
-                Scheduler::cancel($timeout_watcher);
-            }
+        } catch (Throwable $throwable) {
+            $exception = $throwable;
+        }
 
-            if ($state->isComplete()) {
-                // timed-out.
-                return;
-            }
+        if (null !== $timeout_watcher->value) {
+            $timeout_watcher_value = $timeout_watcher->value;
+            $timeout_watcher->value = null;
+            Scheduler::cancel($timeout_watcher_value);
+        } elseif ($state->isComplete()) {
+            // timeout has been reached.
+            return;
+        }
 
+        if (null !== $exception) {
+            $state->error($exception);
+        } else {
             $state->complete($result);
-        } catch (Throwable $throwable) {
-            $state->error($throwable);
         }
     });
 
-
     return new Awaitable($state);
 }
diff --git a/tests/unit/Async/AllTest.php b/tests/unit/Async/AllTest.php
new file mode 100644
index 00000000..652fd288
--- /dev/null
+++ b/tests/unit/Async/AllTest.php
@@ -0,0 +1,110 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Psl\Tests\Unit\Async;
+
+use PHPUnit\Framework\TestCase;
+use Psl;
+use Psl\Async;
+use Psl\Exception\InvariantViolationException;
+
+final class AllTest extends TestCase
+{
+    public function testAll(): void
+    {
+        $awaitables = [
+            'a' => Async\run(static function (): string {
+                Async\usleep(100);
+
+                return 'a';
+            }),
+            'b' => Async\run(static function (): string {
+                Async\usleep(100);
+
+                return 'b';
+            }),
+            'c' => Async\run(static function (): string {
+                Async\usleep(100);
+
+                return 'c';
+            }),
+        ];
+
+        $results = Async\all($awaitables);
+
+        static::assertSame(['a' => 'a', 'b' => 'b', 'c' => 'c'], $results);
+    }
+
+    public function testAllForwardsException(): void
+    {
+        $this->expectException(InvariantViolationException::class);
+        $this->expectExceptionMessage('a');
+
+        Async\all([
+            Async\run(static function (): string {
+                Async\usleep(100);
+
+                throw new InvariantViolationException('a');
+            }),
+            Async\run(static function (): string {
+                Async\usleep(200);
+
+                throw new InvariantViolationException('b');
+            }),
+            Async\run(static function (): string {
+                Async\usleep(300);
+
+                return 'c';
+            }),
+            Async\run(static function (): string {
+                Async\usleep(50);
+
+                Async\later();
+
+                Async\usleep(50);
+
+                return 'c';
+            }),
+        ]);
+    }
+
+    public function testAllAwaitablesAreCompleted(): void
+    {
+        $ref = new Psl\Ref('');
+
+        try {
+            Async\all([
+                Async\run(static function () use ($ref): void {
+                    $ref->value .= 'a';
+
+                    throw new InvariantViolationException('a');
+                }),
+                Async\run(static function () use ($ref): void {
+                    Async\usleep(2000);
+
+                    $ref->value .= 'b';
+
+                    throw new InvariantViolationException('b');
+                }),
+                Async\run(static function () use ($ref): void {
+                    Async\usleep(3000);
+
+                    $ref->value .= 'c';
+                }),
+                Async\run(static function () use ($ref): void {
+                    Async\usleep(500);
+
+                    Async\later();
+
+                    Async\usleep(500);
+
+                    $ref->value .= 'd';
+                }),
+            ]);
+        } catch (InvariantViolationException) {
+        }
+
+        static::assertSame('adbc', $ref->value);
+    }
+}