XmlSerializer and nullable attributes

I had a similar problem with some code I was working on, and I decided just to use a string for the property I was serializing and deserializing. I ended up with something like this:

[XmlAttribute("Age")]
public string Age
{
    get 
    { 
        if (this.age.HasValue)
            return this.age.Value.ToString(); 
        else
            return null;
    }
    set 
    { 
        if (value != null)
            this.age = int.Parse(value);
        else
            this.age = null;
    }
}

[XmlIgnore]
public int? age;