IValueConverter incompatible, Pain level 3

Win8 seems to randomly break IValueConverter by making the last parameter a string instead of CultureInfo!  I haven’t found the correct way to fix this, but at least this compiles Win8 and WP8:

public class BooleanConverter<T> : IValueConverter

{

    public BooleanConverter(T trueValue, T falseValue)

    {

        True = trueValue;

        False = falseValue;

    }

    public T True { get; set; }

    public T False { get; set; }

    public virtual object Convert(object value, Type targetType, object parameter, string language)

    {

        return value is bool && ((bool)value) ? True : False;

    }

    public virtual object ConvertBack(object value, Type targetType, object parameter, string language)

    {

        return value is T && EqualityComparer<T>.Default.Equals((T)value, True);

    }

#if !WINFX_CORE

    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)

    {

        return Convert(value, targetType, parameter, "");

    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)

    {

        return ConvertBack(value, targetType, parameter, "");

    }

#endif

}