--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -5075,19 +5075,20 @@ nsDocument::UnblockDOMContentLoaded()
   MOZ_ASSERT(mBlockDOMContentLoaded);
   if (--mBlockDOMContentLoaded != 0 || mDidFireDOMContentLoaded) {
     return;
   }
   mDidFireDOMContentLoaded = true;
 
   MOZ_ASSERT(mReadyState == READYSTATE_INTERACTIVE);
   if (!mSynchronousDOMContentLoaded) {
+    MOZ_RELEASE_ASSERT(NS_IsMainThread());
     nsCOMPtr<nsIRunnable> ev =
       NewRunnableMethod(this, &nsDocument::DispatchContentLoadedEvents);
-    NS_DispatchToCurrentThread(ev);
+    Dispatch("DispatchContentLoadedEvents", TaskCategory::Other, ev.forget());
   } else {
     DispatchContentLoadedEvents();
   }
 }
 
 void
 nsDocument::ContentStateChanged(nsIContent* aContent, EventStates aStateMask)
 {