diff --git a/content/media/MediaDecoder.cpp b/content/media/MediaDecoder.cpp
index 0b5db4272d7d..a43302761142 100644
--- a/content/media/MediaDecoder.cpp
+++ b/content/media/MediaDecoder.cpp
@@ -1019,8 +1019,13 @@ void MediaDecoder::NotifyPrincipalChanged()
 
 void MediaDecoder::NotifyBytesConsumed(int64_t aBytes, int64_t aOffset)
 {
+  MOZ_ASSERT(NS_IsMainThread());
+  if (mShuttingDown) {
+    return;
+  }
+
   ReentrantMonitorAutoEnter mon(GetReentrantMonitor());
-  NS_ENSURE_TRUE_VOID(mDecoderStateMachine);
+  MOZ_ASSERT(mDecoderStateMachine);
   if (mIgnoreProgressData) {
     return;
   }