Dapper.FluentMap bug for nullable decimal

Question

I was looking to find a simple way to map a class property to a table column and I found Dapper fluent map which I thought was going to be a great alternative to the considerable boilerplate code that one would need to write simply to map a property to a column. But it does not seem to work.

FluentMapper.Initialize(c =>
{
    c.AddMap(new MarginSummaryMap());
});

[Serializable]
[Table("PbCash")]
public class MarginSummary : Entity
{
    public long RunId { get; set; }
    public DateTime? BusinessDate { get; set; }
    [Write(false)]
    public DateTime ProcessDate { get; set; }
    public string Broker { get; set; }
    public string BrokerAccountId { get; set; }
    public string Account { get; set; }
    public string Folio { get; set; }
    public decimal? ActualExcessOrDeficit { get; set; }
    [Write(false)]
    public decimal? ProjectedExcessOrDeficit { get; set; }
    public string Comment { get; set; }
}

public class MarginSummaryMap : EntityMap<MarginSummary>
{
    public MarginSummaryMap()
    {
        Map(c => c.ActualExcessOrDeficit).ToColumn("ExcessOrDeficit");
    }
}

Then when I am trying to save data I get an exception that the column ActualExcessOrDeficit does not exist in the table. Well it does not and the mapping is supposed to convert to the actual column ExcessOrDeficit.

Looks like this is a bug in Dapper.FluentMap since the problem goes way if I change type from decimal? to decimal.

Did anyone have this working - I would love to know how to fix this.