Xamarin.Forms binding with indexers crashes application

When using an object with two indexers, the binding can't resolve it and the application crashes.

For instance, if the following binding is set

<Label Text="{Binding [asdf]}" />

And the BindingContext is an instance of the following class

public class MyClass
{
    public string this[int index]
    {
        get
        {
            return "Accessing through integer indexer";
        }
    }

    public string this[string index]
    {
        get
        {
            return "Accessing through string indexer";
        }
    }
}

an unhandled exception is thrown.

if the integer indexer is commented the binding works fine.

Regards,
Alvaro.