Back Arrow Color on Lollipop with FormsAppCompatActivity

What is the proper way to change the back arrow color when using FormsAppCompatActivity?

I created a new project and followed the instructions here to use Material Design:

https://blog.xamarin.com/material-design-for-your-xamarin-forms-android-apps/

On KitKat, I see white text and a white arrow with a NavigationPage, however on Lollipop I get white text and a dark arrow that's #0f456f (black with 54% opacity over #2196f3).

Here's the basic code I used to test this:

public class App : Application
{
    public App ()
    {
        var page1 = new ContentPage () {
            Title = "Page 1"
        };

        page1.Navigation.PushAsync (new ContentPage () {
            Title = "Page 2",
            Content = new SearchBar () {
                Text = "This should remain dark."
            }
        });

        MainPage = new NavigationPage (page1) {
            BarTextColor = Color.White
        };

    }
}

(Full project attached)

I tried using colorControlNormal in the style, but that also changed other controls (e.g. SearchBar). I'd like to only change the color of the back arrow.

Thanks!