when undertook original deal (welldriller hits rock and asks for higher price to finish job), most moderncourts will find modification binding). UCC:pre-existing duty rule doesn’t apply to contract modification. Needs no consideration to be binding. UCC 2-209 belowFoakes v. Beer (House of Lords, 1884)F: Beer (P) agreed to forego interest on a debt if Foakes (D) would pay her part of the debt immediately and the remainder in installments. R: There is no consideration present where the debtor makes a new agreement to do that which he is already obligated to do. P obtained no advantage. Court’s shouldn’t judge adequacy, but not consideration whatsoever present.Restatement §73 comment c (p290):Slight variations of circumstance are commonly held to take a case out of the rule, particular where parties have made an equitable adjustment in the course of performance of a continuing contract, or where an impecunious debtor has pai part of his debt in satisfaction of the whole – some state the rule has simply been repudiated.