--- a/dom/media/MediaManager.cpp
+++ b/dom/media/MediaManager.cpp
@@ -2063,29 +2063,46 @@ MediaManager::EnumerateDevices(nsPIDOMWi
                                nsIDOMGetUserMediaErrorCallback* aOnFailure)
 {
   MOZ_ASSERT(NS_IsMainThread());
   NS_ENSURE_TRUE(!sInShutdown, NS_ERROR_FAILURE);
   nsCOMPtr<nsIGetUserMediaDevicesSuccessCallback> onSuccess(aOnSuccess);
   nsCOMPtr<nsIDOMGetUserMediaErrorCallback> onFailure(aOnFailure);
   uint64_t windowId = aWindow->WindowID();
 
-  AddWindowID(windowId);
+  StreamListeners* listeners = AddWindowID(windowId);
+
+  // Create a disabled listener to act as a placeholder
+  nsRefPtr<GetUserMediaCallbackMediaStreamListener> listener =
+    new GetUserMediaCallbackMediaStreamListener(mMediaThread, windowId);
+
+  // No need for locking because we always do this in the main thread.
+  listeners->AppendElement(listener);
 
   bool fake = Preferences::GetBool("media.navigator.streams.fake");
 
   nsRefPtr<PledgeSourceSet> p = EnumerateDevicesImpl(windowId,
                                                      dom::MediaSourceEnum::Camera,
                                                      dom::MediaSourceEnum::Microphone,
                                                      fake);
-  p->Then([onSuccess](SourceSet*& aDevices) mutable {
+  p->Then([onSuccess, windowId, listener](SourceSet*& aDevices) mutable {
     ScopedDeletePtr<SourceSet> devices(aDevices); // grab result
+    nsRefPtr<MediaManager> mgr = MediaManager_GetInstance();
+    if (!mgr) {
+      return;
+    }
+    mgr->RemoveFromWindowList(windowId, listener);
     nsCOMPtr<nsIWritableVariant> array = MediaManager_ToJSArray(*devices);
     onSuccess->OnSuccess(array);
-  }, [onFailure](MediaStreamError& reason) mutable {
+  }, [onFailure, windowId, listener](MediaStreamError& reason) mutable {
+    nsRefPtr<MediaManager> mgr = MediaManager_GetInstance();
+    if (!mgr) {
+      return;
+    }
+    mgr->RemoveFromWindowList(windowId, listener);
     onFailure->OnError(&reason);
   });
   return NS_OK;
 }
 
 /*
  * GetUserMediaDevices - called by the UI-part of getUserMedia from chrome JS.
  */