--- a/dom/media/webrtc/MediaTrackConstraints.cpp
+++ b/dom/media/webrtc/MediaTrackConstraints.cpp
@@ -598,17 +598,17 @@ MediaConstraintsHelper::FindBadConstrain
 {
   AutoTArray<RefPtr<MediaDevice>, 1> devices;
   devices.AppendElement(MakeRefPtr<MediaDevice>(aMediaEngineSource,
                                                 aMediaEngineSource->GetName(),
                                                 aDeviceId));
   return FindBadConstraint(aConstraints, devices);
 }
 
-void
+/* static */ void
 MediaConstraintsHelper::ConvertOldWithWarning(
     const dom::OwningBooleanOrConstrainBooleanParameters& old,
     dom::OwningBooleanOrConstrainBooleanParameters& to,
     const char* aMessageName,
     nsPIDOMWindowInner* aWindow) {
   if ((old.IsBoolean() ||
        old.GetAsConstrainBooleanParameters().mExact.WasPassed() ||
        old.GetAsConstrainBooleanParameters().mIdeal.WasPassed()) &&