entity framework property can't be set to string, has to be nullable int

The 'EmpGipNumber' property on 'Employee' could not be set to a 'System.String' value. You must set this property to a non-null value of type 'System.Int32'.

I'm getting this error, and my Employee Model's EmpGipNumber property is declared like this:

public virtual int? EmpGipNumber {get;set;}

why is it complaining, its a nullable int already. Ever since I enabled migrations I've been running into a large amount of problems.

The initial migration is empty because I enabled migrations on an existing database. The second migration is this:

public override void Up()
        {
            AlterColumn("dbo.Employee", "EmpGipNumber", c => c.Int());
        }

it was working fine yesterday. Me going to sleep must've angered it