Repro exception posting an object with an enum

gistfile1.cs

using System.Net;
using EasyHttp.Http;
using Should.Fluent;
using Xunit;

namespace Tests
{
    public class HttpClientTests
    {
        [Fact]
        public void Post_WhenUriIsMissingOnServer_ShouldRespondNotFound()
        {
            var client = new HttpClient();
            client.Post("http://graemef.com/thisdoesnotexist", new Foo(), "application/vnd.fubar+json");

            client.Response.StatusCode.Should().Equal(HttpStatusCode.NotFound);
        }
    }

    public class Foo
    {
        public Bar Baz { get; set; }
    }

    public enum Bar
    {
        First,
        Second,
        Third
    }
}