diff --git a/dom/plugins/ipc/PluginInstanceChild.cpp b/dom/plugins/ipc/PluginInstanceChild.cpp
index 4425fbc86c40..e978307323cc 100644
--- a/dom/plugins/ipc/PluginInstanceChild.cpp
+++ b/dom/plugins/ipc/PluginInstanceChild.cpp
@@ -2365,11 +2365,7 @@ PluginInstanceChild::RecvAsyncNPP_NewStream(PBrowserStreamChild* actor,
     BrowserStreamChild* child = static_cast<BrowserStreamChild*>(actor);
     NewStreamAsyncCall* task = new NewStreamAsyncCall(this, child, mimeType,
                                                       seekable);
-    {
-        MutexAutoLock lock(mAsyncCallMutex);
-        mPendingAsyncCalls.AppendElement(task);
-    }
-    MessageLoop::current()->PostTask(FROM_HERE, task);
+    PostChildAsyncCall(task);
     return true;
 }
 
@@ -3645,12 +3641,17 @@ void
 PluginInstanceChild::AsyncCall(PluginThreadCallback aFunc, void* aUserData)
 {
     ChildAsyncCall* task = new ChildAsyncCall(this, aFunc, aUserData);
+    PostChildAsyncCall(task);
+}
 
+void
+PluginInstanceChild::PostChildAsyncCall(ChildAsyncCall* aTask)
+{
     {
         MutexAutoLock lock(mAsyncCallMutex);
-        mPendingAsyncCalls.AppendElement(task);
+        mPendingAsyncCalls.AppendElement(aTask);
     }
-    ProcessChild::message_loop()->PostTask(FROM_HERE, task);
+    ProcessChild::message_loop()->PostTask(FROM_HERE, aTask);
 }
 
 static PLDHashOperator
diff --git a/dom/plugins/ipc/PluginInstanceChild.h b/dom/plugins/ipc/PluginInstanceChild.h
index 04eaf2aacdd8..2fc5a75d66fc 100644
--- a/dom/plugins/ipc/PluginInstanceChild.h
+++ b/dom/plugins/ipc/PluginInstanceChild.h
@@ -245,6 +245,8 @@ public:
     void UnscheduleTimer(uint32_t id);
 
     void AsyncCall(PluginThreadCallback aFunc, void* aUserData);
+    // This function is a more general version of AsyncCall
+    void PostChildAsyncCall(ChildAsyncCall* aTask);
 
     int GetQuirks();
 
diff --git a/dom/plugins/ipc/PluginModuleChild.cpp b/dom/plugins/ipc/PluginModuleChild.cpp
index 08d7af74d22c..513cddf01219 100644
--- a/dom/plugins/ipc/PluginModuleChild.cpp
+++ b/dom/plugins/ipc/PluginModuleChild.cpp
@@ -2177,6 +2177,26 @@ PluginModuleChild::AnswerSyncNPP_New(PPluginInstanceChild* aActor, NPError* rv)
     return true;
 }
 
+class AsyncNewResultSender : public ChildAsyncCall
+{
+public:
+    AsyncNewResultSender(PluginInstanceChild* aInstance, NPError aResult)
+        : ChildAsyncCall(aInstance, nullptr, nullptr)
+        , mResult(aResult)
+    {
+    }
+
+    void Run() override
+    {
+        RemoveFromAsyncList();
+        DebugOnly<bool> sendOk = mInstance->SendAsyncNPP_NewResult(mResult);
+        MOZ_ASSERT(sendOk);
+    }
+
+private:
+    NPError  mResult;
+};
+
 bool
 PluginModuleChild::RecvAsyncNPP_New(PPluginInstanceChild* aActor)
 {
@@ -2185,7 +2205,8 @@ PluginModuleChild::RecvAsyncNPP_New(PPluginInstanceChild* aActor)
         reinterpret_cast<PluginInstanceChild*>(aActor);
     AssertPluginThread();
     NPError rv = childInstance->DoNPP_New();
-    childInstance->SendAsyncNPP_NewResult(rv);
+    AsyncNewResultSender* task = new AsyncNewResultSender(childInstance, rv);
+    childInstance->PostChildAsyncCall(task);
     return true;
 }