--- a/dom/indexedDB/IDBTransaction.cpp
+++ b/dom/indexedDB/IDBTransaction.cpp
@@ -234,16 +234,21 @@ IDBTransaction::Create(JSContext* aCx, I
     WorkerPrivate* workerPrivate = GetCurrentThreadWorkerPrivate();
     MOZ_ASSERT(workerPrivate);
 
     workerPrivate->AssertIsOnWorkerThread();
 
     nsAutoPtr<WorkerHolder> workerHolder(
       new WorkerHolder(workerPrivate, transaction));
     if (NS_WARN_IF(!workerHolder->HoldWorker(workerPrivate, Canceling))) {
+      // Silence the destructor assertion if we never made this object live.
+#ifdef DEBUG
+      MOZ_ASSERT(!transaction->mSentCommitOrAbort);
+      transaction->mSentCommitOrAbort = true;
+#endif
       return nullptr;
     }
 
     transaction->mWorkerHolder = Move(workerHolder);
   }
 
   nsCOMPtr<nsIRunnable> runnable = do_QueryObject(transaction);
   nsContentUtils::RunInMetastableState(runnable.forget());