diff --git a/dom/messagechannel/MessagePort.cpp b/dom/messagechannel/MessagePort.cpp
index a63c84b2b0..5fbd1e9bb9 100644
--- a/dom/messagechannel/MessagePort.cpp
+++ b/dom/messagechannel/MessagePort.cpp
@@ -495,6 +495,14 @@ MessagePort::PostMessage(JSContext* aCx,
   mActor->SendPostMessages(messages);
 }
 
+void
+MessagePort::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
+                         const StructuredSerializeOptions& aOptions,
+                         ErrorResult& aRv)
+{
+  PostMessage(aCx, aMessage, aOptions.mTransfer, aRv);
+}
+
 void
 MessagePort::Start()
 {
diff --git a/dom/messagechannel/MessagePort.h b/dom/messagechannel/MessagePort.h
index e635c532a3..b832872e1f 100644
--- a/dom/messagechannel/MessagePort.h
+++ b/dom/messagechannel/MessagePort.h
@@ -26,6 +26,7 @@ class MessagePortIdentifier;
 class MessagePortMessage;
 class PostMessageRunnable;
 class SharedMessagePortMessage;
+struct StructuredSerializeOptions;
 
 namespace workers {
 class WorkerHolder;
@@ -65,6 +66,11 @@ public:
               const Sequence<JSObject*>& aTransferable,
               ErrorResult& aRv);
 
+  void
+  PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
+              const StructuredSerializeOptions& aOptions,
+              ErrorResult& aRv);
+
   void Start();
 
   void Close();
diff --git a/dom/webidl/MessagePort.webidl b/dom/webidl/MessagePort.webidl
index 6495b5616d..0b36c47d94 100644
--- a/dom/webidl/MessagePort.webidl
+++ b/dom/webidl/MessagePort.webidl
@@ -10,7 +10,9 @@
 [Exposed=(Window,Worker,System)]
 interface MessagePort : EventTarget {
   [Throws]
-  void postMessage(any message, optional sequence<object> transferable = []);
+  void postMessage(any message, sequence<object> transferable);
+  [Throws]
+  void postMessage(any message, optional StructuredSerializeOptions options);
 
   void start();
   void close();
@@ -19,3 +21,8 @@ interface MessagePort : EventTarget {
   attribute EventHandler onmessage;
 };
 // MessagePort implements Transferable;
+
+// Used to declare which objects should be transferred.
+dictionary StructuredSerializeOptions {
+  sequence<object> transfer = [];
+};
\ No newline at end of file