An agreement to forbear to sue in consideration of a written promise by a third person to pay the debt of another constitutes a valid contract. Markel v. DiFrancesco, 93 Conn. 355, 359, 105 A. 703; Waters v. White, 75 Conn. 88, 91, 52 A. 401; see also Savings Bank of Rockville v. Cohn, 116 Conn. 480, 485, 165 A. 607; 1 Williston, Contracts (Rev. Ed.) 135. From the finding now before us, with the necessary corrections, it appears that the defendant's parents owed the plaintiff the sum in suit; that it was an existing debt; that the plaintiff demanded payment of it; and that as a result the defendant signed the forbearance contract. On these facts, the trial court was in error in ruling that the contract was invalid.

The agreement to forbear by one when accepted by another and acted upon is a sufficient consideration. Waters v. White, 75 Conn. 88, 52 A. 401. A second criticism of the charge is that it is adapted to the defense of fraudulent representations, and not to that of a unilateral mistake known to the other party and taken advantage of by him.