diff --git a/dom/media/MediaDecoder.cpp b/dom/media/MediaDecoder.cpp
index 9b8c82d1654d..9593217bf8d5 100644
--- a/dom/media/MediaDecoder.cpp
+++ b/dom/media/MediaDecoder.cpp
@@ -535,7 +535,7 @@ void MediaDecoder::AddOutputStream(ProcessedMediaStream* aStream,
   {
     ReentrantMonitorAutoEnter mon(GetReentrantMonitor());
     if (mDecoderStateMachine) {
-      mDecoderStateMachine->SetAudioCaptured();
+      mDecoderStateMachine->DispatchAudioCaptured();
     }
     if (!GetDecodedStream()) {
       int64_t t = mDecoderStateMachine ?
@@ -748,7 +748,7 @@ void MediaDecoder::SetStateMachineParameters()
   ReentrantMonitorAutoEnter mon(GetReentrantMonitor());
   mDecoderStateMachine->SetDuration(mDuration);
   if (GetDecodedStream()) {
-    mDecoderStateMachine->SetAudioCaptured();
+    mDecoderStateMachine->DispatchAudioCaptured();
   }
   if (mMinimizePreroll) {
     mDecoderStateMachine->SetMinimizePrerollUntilPlaybackStarts();
diff --git a/dom/media/MediaDecoderStateMachine.cpp b/dom/media/MediaDecoderStateMachine.cpp
index c9a6d293b082..4fcffd00af09 100644
--- a/dom/media/MediaDecoderStateMachine.cpp
+++ b/dom/media/MediaDecoderStateMachine.cpp
@@ -1372,17 +1372,6 @@ void MediaDecoderStateMachine::VolumeChanged()
   }
 }
 
-void MediaDecoderStateMachine::SetAudioCaptured()
-{
-  NS_ASSERTION(NS_IsMainThread(), "Should be on main thread.");
-  AssertCurrentThreadInMonitor();
-  if (!mAudioCaptured) {
-    mAudioCaptured = true;
-    // Schedule the state machine to send stream data as soon as possible.
-    ScheduleStateMachine();
-  }
-}
-
 double MediaDecoderStateMachine::GetCurrentTime() const
 {
   return static_cast<double>(mCurrentFrameTime) / static_cast<double>(USECS_PER_S);
diff --git a/dom/media/MediaDecoderStateMachine.h b/dom/media/MediaDecoderStateMachine.h
index 4104690be21f..6eb09c8b17ea 100644
--- a/dom/media/MediaDecoderStateMachine.h
+++ b/dom/media/MediaDecoderStateMachine.h
@@ -152,7 +152,20 @@ public:
     return mState;
   }
 
-  void SetAudioCaptured();
+  void DispatchAudioCaptured()
+  {
+    nsRefPtr<MediaDecoderStateMachine> self = this;
+    nsCOMPtr<nsIRunnable> r = NS_NewRunnableFunction([self] () -> void
+    {
+      MOZ_ASSERT(self->OnTaskQueue());
+      ReentrantMonitorAutoEnter mon(self->mDecoder->GetReentrantMonitor());
+      if (!self->mAudioCaptured) {
+        self->mAudioCaptured = true;
+        self->ScheduleStateMachine();
+      }
+    });
+    TaskQueue()->Dispatch(r.forget());
+  }
 
   // Check if the decoder needs to become dormant state.
   bool IsDormantNeeded();