We reverse the directed verdict entered in favor of the defendant upon a finding that the plaintiff had at least made out a prima facie case for recovery of a debt on a simple contract. See Locke v. Aetna Acceptance Corp., 309 So.2d 43 (Fla. 1st DCA 1975). See generally 6 Fla.Jur.2d Bills and Notes § 21. We further hold that the court erred in finding the instrument nonnegotiable because it was payable out of “restaurant earnings.” Payment was not conditioned to be made only out of that source. § 673.105(1)(f), Fla.Stat. (1975); Wright v. Board of Public Instruction for County of Sumter, 77 So.2d 435, 437 (Fla. 1955); Barnett Bank of Palm Beach County, N.A. v. Regency Highland Condominium Association, 452 So.2d 587 (Fla. 4th DCA 1984).