--- a/dom/media/MediaCache.cpp
+++ b/dom/media/MediaCache.cpp
@@ -1744,16 +1744,20 @@ MediaCacheStream::UpdatePrincipal(nsIPri
 }
 
 void
 MediaCacheStream::NotifyDataReceived(int64_t aSize, const char* aData,
     nsIPrincipal* aPrincipal)
 {
   NS_ASSERTION(NS_IsMainThread(), "Only call on main thread");
 
+  if (mClosed) {
+    return;
+  }
+
   // Update principals before putting the data in the cache. This is important,
   // we want to make sure all principals are updated before any consumer
   // can see the new data.
   // We do this without holding the cache monitor, in case the client wants
   // to do something that takes a lock.
   {
     MediaCache::ResourceStreamIterator iter(mResourceID);
     while (MediaCacheStream* stream = iter.Next()) {