Protobuf.net: how to handle inheritance without [ProtoInclude]

I am using Protobuf.net to serialize some classes. I would like to be able to serialize the SuperHero class (below) without having to specify [ProtoInclude] on the base class. This is because the derived classes are automatically generated but the base class is not, so the base class does not directly know about its derived classes.

    [ProtoContract]
    class Person
    {
        [ProtoMember(1)]
        public int Id { get; set; }
        [ProtoMember(2)]
        public string Name { get; set; }
    }

    [ProtoContract]
    class SuperHero : Person
    {
        [ProtoMember(3)]
        public string Powers { get; set; }
    }

I am using the latest version of protobuf.net.