Overpayment of taxes from the from prior year

The IRS sent me a notification that the over payment of taxes I asked to apply to the following year was off by I think 40.00. That still leaves me with a significant credit of over 4,000. But should I just override the incorrect amount on this year's return or do I have to amend something? I have no idea what would need amending as they didn't say what the issue was.