diff --git a/src/Internal/Workflow/WorkflowContext.php b/src/Internal/Workflow/WorkflowContext.php
index 680e7d4b..3f42be58 100644
--- a/src/Internal/Workflow/WorkflowContext.php
+++ b/src/Internal/Workflow/WorkflowContext.php
@@ -61,7 +61,7 @@
 use Temporal\Workflow\ChildWorkflowStubInterface;
 use Temporal\Workflow\ContinueAsNewOptions;
 use Temporal\Workflow\ExternalWorkflowStubInterface;
-use Temporal\Workflow\MutexInterface;
+use Temporal\Workflow\Mutex;
 use Temporal\Workflow\WorkflowContextInterface;
 use Temporal\Workflow\WorkflowExecution;
 use Temporal\Workflow\WorkflowInfo;
@@ -642,16 +642,6 @@ public function uuid7(?\DateTimeInterface $dateTime = null): PromiseInterface
         return $this->sideEffect(static fn(): UuidInterface => \Ramsey\Uuid\Uuid::uuid7($dateTime));
     }
 
-    public function mutex(): MutexInterface
-    {
-        // todo
-    }
-
-    public function runLocked(MutexInterface $mutex, callable $callable): PromiseInterface
-    {
-        // todo
-    }
-
     /**
      * @internal
      */
diff --git a/src/Workflow.php b/src/Workflow.php
index 6e296d46..497c2f31 100644
--- a/src/Workflow.php
+++ b/src/Workflow.php
@@ -27,7 +27,7 @@
 use Temporal\Workflow\ChildWorkflowStubInterface;
 use Temporal\Workflow\ContinueAsNewOptions;
 use Temporal\Workflow\ExternalWorkflowStubInterface;
-use Temporal\Workflow\MutexInterface;
+use Temporal\Workflow\Mutex;
 use Temporal\Workflow\ScopedContextInterface;
 use Temporal\Workflow\UpdateContext;
 use Temporal\Workflow\WorkflowContextInterface;
@@ -996,45 +996,24 @@ public static function uuid7(?\DateTimeInterface $dateTime = null): PromiseInter
         return $context->uuid7($dateTime);
     }
 
-    /**
-     * Create a new mutex.
-     *
-     * If a mutex is yielded without calling `lock()`, the Workflow will continue
-     * only when the lock is released.
-     *
-     * ```php
-     * $this->>mutex = Workflow::mutex();
-     *
-     * // Continue only when the lock is released
-     * yield $this->mutex;
-     *
-     * // Continue only when the lock is acquired
-     * yield Workflow::mutex('my-mutex')->lock();
-     * ```
-     *
-     * Note: in the last case, if the lock is already acquired, the Workflow will be blocked until it's released.
-     */
-    public static function mutex(): MutexInterface
-    {
-        /** @var WorkflowContextInterface $context */
-        $context = self::getCurrentContext();
-
-        return $context->mutex();
-    }
-
     /**
      * Run a function when the mutex is released.
      * The mutex is locked for the duration of the function.
      *
-     * @param non-empty-string|MutexInterface $mutex Mutex name or instance.
-     *@see Workflow::conditionalMutex()
+     * @template T
+     * @param Mutex $mutex Mutex name or instance.
+     * @param callable(): T $callable Function to run.
      *
+     * @return PromiseInterface<T>
      */
-    public function runLocked(string|MutexInterface $mutex, callable $callable): PromiseInterface
+    public function runLocked(Mutex $mutex, callable $callable): PromiseInterface
     {
-        /** @var WorkflowContextInterface $context */
-        $context = self::getCurrentContext();
-
-        return $context->runLocked($mutex, $callable);
+        return $mutex->lock()->then(static function (Mutex $mutex) use ($callable): mixed {
+            try {
+                return $callable();
+            } finally {
+                $mutex->unlock();
+            }
+        });
     }
 }
diff --git a/src/Workflow/Mutex.php b/src/Workflow/Mutex.php
new file mode 100644
index 00000000..639d4b6c
--- /dev/null
+++ b/src/Workflow/Mutex.php
@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Temporal\Workflow;
+
+use React\Promise\Deferred;
+use React\Promise\PromiseInterface;
+use Temporal\Promise;
+
+/**
+ * If a mutex is yielded without calling `lock()`, the Workflow will continue
+ * only when the lock is released.
+ *
+ * ```
+ *  $this->mutex = new Mutex();
+ *
+ *  // Continue only when the lock is released
+ *  yield $this->mutex;
+ * ```
+ */
+final class Mutex
+{
+    private bool $locked = false;
+
+    /** @var Deferred[] */
+    private array $waiters = [];
+
+    /**
+     * Lock the mutex.
+     *
+     * ```
+     *  // Continue only when the lock is acquired
+     *  yield $this->mutex->lock();
+     * ```
+     *
+     * @return PromiseInterface A promise that resolves when the lock is acquired.
+     */
+    public function lock(): PromiseInterface
+    {
+        if (!$this->locked) {
+            $this->locked = true;
+            return Promise::resolve($this);
+        }
+
+        $deferred = new Deferred();
+        $this->waiters[] = $deferred;
+
+        return $deferred->promise();
+    }
+
+    /**
+     * Try to lock the mutex.
+     *
+     * @return bool Returns true if the mutex was successfully locked, false otherwise.
+     */
+    public function tryLock(): bool
+    {
+        return !$this->locked and $this->locked = true;
+    }
+
+    /**
+     * Release the lock.
+     */
+    public function unlock(): void
+    {
+        if ($this->waiters === []) {
+            $this->locked = false;
+            return;
+        }
+
+        \array_shift($this->waiters)->resolve($this);
+    }
+
+    /**
+     * Check if the mutex is locked.
+     */
+    public function isLocked(): bool
+    {
+        return $this->locked;
+    }
+}
diff --git a/src/Workflow/MutexInterface.php b/src/Workflow/MutexInterface.php
deleted file mode 100644
index 54298da1..00000000
--- a/src/Workflow/MutexInterface.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Temporal\Workflow;
-
-use React\Promise\PromiseInterface;
-
-interface MutexInterface
-{
-    public function lock(): PromiseInterface;
-
-    /**
-     * Try to lock the mutex.
-     *
-     * @return bool true if the mutex was successfully locked, false otherwise.
-     */
-    public function tryLock(): bool;
-
-    public function unlock(): void;
-
-    public function isLocked(): bool;
-}
diff --git a/src/Workflow/WorkflowContextInterface.php b/src/Workflow/WorkflowContextInterface.php
index 05d77886..90e5debf 100644
--- a/src/Workflow/WorkflowContextInterface.php
+++ b/src/Workflow/WorkflowContextInterface.php
@@ -384,15 +384,4 @@ public function uuid4(): PromiseInterface;
      * @return PromiseInterface<UuidInterface>
      */
     public function uuid7(?\DateTimeInterface $dateTime = null): PromiseInterface;
-
-    /**
-     * Create a mutex.
-     */
-    public function mutex(): MutexInterface;
-
-    /**
-     * Run a function when the mutex is released.
-     * The mutex will be locked for the duration of the function.
-     */
-    public function runLocked(MutexInterface $mutex, callable $callable): PromiseInterface;
 }