EF 4.3 migration renaming column instead of deleting it

I have this class:

public class HabitDo{
    public int? HabitId { get; set; }
    virtual public Habit Habit { get; set; }

    public int DoId { get; set; }
    virtual public Do Do { get; set; }

    public string Restriction { get; set; }

    public int? ObjectiveId { get; set; }
    public Objective Objective { get; set; }

    public virtual ICollection<DoObjective> Objectives { get; set; }
}

The table is just fine, but then I remove from code the Objective property:

 public class HabitDo{
    public int? HabitId { get; set; }
    virtual public Habit Habit { get; set; }

    public int DoId { get; set; }
    virtual public Do Do { get; set; }

    public string Restriction { get; set; }

    public virtual ICollection<DoObjective> Objectives { get; set; }
}

And when calling update-database from the manager console EF renames the ObjectiveId column instead of dropping it:

    EXECUTE sp_rename @objname = N'HabitDoes.ObjectiveId', @newname =  N'Objective_Id', @objtype = N'COLUMN'

Any clues why this happens?