--- a/dom/media/gmp/GMPServiceParent.cpp
+++ b/dom/media/gmp/GMPServiceParent.cpp
@@ -899,17 +899,19 @@ GeckoMediaPluginServiceParent::AsyncAddP
 {
   RefPtr<AbstractThread> thread(GetAbstractGMPThread());
   if (!thread) {
     return GenericPromise::CreateAndReject(NS_ERROR_FAILURE, __func__);
   }
 
   nsString dir(aDirectory);
   RefPtr<GeckoMediaPluginServiceParent> self = this;
-  return InvokeAsync(thread, this, __func__, &GeckoMediaPluginServiceParent::AddOnGMPThread, dir)
+  return InvokeAsync<nsString&&>(
+           thread, this, __func__,
+           &GeckoMediaPluginServiceParent::AddOnGMPThread, dir)
     ->Then(AbstractThread::MainThread(), __func__,
       [dir, self]() -> void {
         LOGD(("GeckoMediaPluginServiceParent::AsyncAddPluginDirectory %s succeeded",
               NS_ConvertUTF16toUTF8(dir).get()));
         MOZ_ASSERT(NS_IsMainThread());
         self->UpdateContentProcessGMPCapabilities();
       },
       [dir]() -> void {