diff --git a/dom/webidl/Client.webidl b/dom/webidl/Client.webidl
index 7abb65ab1..c961c2b31 100644
--- a/dom/webidl/Client.webidl
+++ b/dom/webidl/Client.webidl
@@ -15,7 +15,9 @@ interface Client {
   readonly attribute DOMString id;
 
   [Throws]
-  void postMessage(any message, optional sequence<object> transfer = []);
+  void postMessage(any message, sequence<object> transferable);
+  [Throws]
+  void postMessage(any message, optional StructuredSerializeOptions options);
 };
 
 [Exposed=ServiceWorker]
diff --git a/dom/webidl/ServiceWorker.webidl b/dom/webidl/ServiceWorker.webidl
index 6dab46a16..ff80fafc2 100644
--- a/dom/webidl/ServiceWorker.webidl
+++ b/dom/webidl/ServiceWorker.webidl
@@ -20,7 +20,9 @@ interface ServiceWorker : EventTarget {
   attribute EventHandler onstatechange;
 
   [Throws]
-  void postMessage(any message, optional sequence<object> transferable = []);
+  void postMessage(any message, sequence<object> transferable);
+  [Throws]
+  void postMessage(any message, optional StructuredSerializeOptions options);
 };
 
 ServiceWorker implements AbstractWorker;
diff --git a/dom/workers/ServiceWorker.cpp b/dom/workers/ServiceWorker.cpp
index f2be038d6..a1b38b248 100644
--- a/dom/workers/ServiceWorker.cpp
+++ b/dom/workers/ServiceWorker.cpp
@@ -15,6 +15,7 @@
 
 #include "mozilla/Preferences.h"
 #include "mozilla/dom/Promise.h"
+#include "mozilla/dom/MessagePortBinding.h"
 #include "mozilla/dom/ServiceWorkerGlobalScopeBinding.h"
 
 #ifdef XP_WIN
@@ -98,6 +99,15 @@ ServiceWorker::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
   aRv = workerPrivate->SendMessageEvent(aCx, aMessage, aTransferable, Move(clientInfo));
 }
 
+void
+ServiceWorker::PostMessage(JSContext* aCx,
+                           JS::Handle<JS::Value> aMessage,
+                           const StructuredSerializeOptions& aOptions,
+                           ErrorResult& aRv)
+{
+  PostMessage(aCx, aMessage, aOptions.mTransfer, aRv);
+}
+
 } // namespace workers
 } // namespace dom
 } // namespace mozilla
diff --git a/dom/workers/ServiceWorker.h b/dom/workers/ServiceWorker.h
index 01f6973c6..7c046a05c 100644
--- a/dom/workers/ServiceWorker.h
+++ b/dom/workers/ServiceWorker.h
@@ -16,6 +16,8 @@ class nsPIDOMWindowInner;
 namespace mozilla {
 namespace dom {
 
+struct StructuredSerializeOptions;
+
 namespace workers {
 
 class ServiceWorkerInfo;
@@ -67,6 +69,12 @@ public:
               const Sequence<JSObject*>& aTransferable,
               ErrorResult& aRv);
 
+  void
+  PostMessage(JSContext* aCx,
+              JS::Handle<JS::Value> aMessage,
+              const StructuredSerializeOptions& aOptions,
+              ErrorResult& aRv);
+
 private:
   // This class can only be created from ServiceWorkerInfo::GetOrCreateInstance().
   ServiceWorker(nsPIDOMWindowInner* aWindow, ServiceWorkerInfo* aInfo);
diff --git a/dom/workers/ServiceWorkerClient.cpp b/dom/workers/ServiceWorkerClient.cpp
index 783efa68a..1f6e4da3a 100644
--- a/dom/workers/ServiceWorkerClient.cpp
+++ b/dom/workers/ServiceWorkerClient.cpp
@@ -12,6 +12,7 @@
 #include "mozilla/dom/Navigator.h"
 #include "mozilla/dom/ServiceWorkerMessageEvent.h"
 #include "mozilla/dom/ServiceWorkerMessageEventBinding.h"
+#include "mozilla/dom/MessagePortBinding.h"
 #include "nsGlobalWindow.h"
 #include "nsIBrowserDOMWindow.h"
 #include "nsIDocument.h"
@@ -221,3 +222,11 @@ ServiceWorkerClient::PostMessage(JSContext* aCx, JS::Handle<JS::Value> aMessage,
   }
 }
 
+void
+ServiceWorkerClient::PostMessage(JSContext* aCx,
+                                 JS::Handle<JS::Value> aMessage,
+                                 const StructuredSerializeOptions& aOptions,
+                                 ErrorResult& aRv)
+{
+  PostMessage(aCx, aMessage, aOptions.mTransfer, aRv);
+}
diff --git a/dom/workers/ServiceWorkerClient.h b/dom/workers/ServiceWorkerClient.h
index a3f2027d9..0bb9c3176 100644
--- a/dom/workers/ServiceWorkerClient.h
+++ b/dom/workers/ServiceWorkerClient.h
@@ -95,6 +95,12 @@ public:
               const Sequence<JSObject*>& aTransferable,
               ErrorResult& aRv);
 
+  void
+  PostMessage(JSContext* aCx,
+              JS::Handle<JS::Value> aMessage,
+              const StructuredSerializeOptions& aOptions,
+              ErrorResult& aRv);
+
   JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
 
 protected: