--- a/dom/media/MediaManager.cpp
+++ b/dom/media/MediaManager.cpp
@@ -1812,19 +1812,17 @@ MediaManager::EnumerateRawDevices(uint64
     if (hasAudio) {
       nsTArray<RefPtr<MediaDevice>> audios;
       GetSources(fakeMics? fakeBackend : realBackend, aAudioType,
                  audios, audioLoopDev.get());
       for (auto& source : audios) {
         result->AppendElement(source);
       }
     }
-    SourceSet* handoff = result.release();
-    NS_DispatchToMainThread(NewRunnableFrom([id, handoff]() mutable {
-      UniquePtr<SourceSet> result(handoff); // grab result
+    NS_DispatchToMainThread(NewRunnableFrom([id, result{Move(result)}]() mutable {
       MediaManager* mgr = MediaManager::GetIfExists();
       if (!mgr) {
         return NS_OK;
       }
       RefPtr<PledgeSourceSet> p = mgr->mOutstandingPledges.Remove(id);
       if (p) {
         p->Resolve(result.release());
       }