EF DatabaseGeneratedOption.Identity attribute does not work for ulong type

[Table( "User" )]
public class User
{
    [Key]
    [DatabaseGeneratedAttribute( DatabaseGeneratedOption.Identity )]
    public ulong Id { get; set; }
    // other columns
}

      

        
        
        
      

    

For this code, I am getting an exception:

System.Data.Entity.Edm.EdmEntityType :: EntityType "User" has no key defined. Define a key for this EntityType.

But changing the id type to int, everything works fine.

    //...
    [DatabaseGeneratedAttribute( DatabaseGeneratedOption.Identity )]
    public int Id { get; set; }
    //...

      

        
        
        
      

    

How do I get the ability to auto-create tables with an identifier having a capacity of type ulong? (obviously using ef code)