Order and judgment unanimously modified on the law and as modified affirmed without costs, , in accordance with the following Memorandum: Supreme Court properly refused to defer determination of plaintiffs partial summary judgment motion pursuant to CPLR 3212 (f). The affidavit of defendant’s attorney, made without knowledge of the facts, was insufficient to establish *968that disclosure might yield facts that would substantiate a defense to plaintiff’s cause of action (see, Weintraub v Phillips, Nizer, Benjamin, Krim & Ballon, 172 AD2d 254; State of New York v Wisser Co., 170 AD2d 918; Limpar Realty Corp. v Uswiss Realty Holding, 112 AD2d 834, 837; see also, Carothers v United Technologies, 177 AD2d 995 [decided herewith]).
Supreme Court, however, erred in assessing damages against defendant when it applied an annual interest rate of 18% for the periods between the dates that defendant’s obligations accrued and the date of judgment. The contract between the parties did not specify an interest rate to be applied to overdue payments, and plaintiff presented no evidence showing that defendant agreed to pay 18%, which was merely included on plaintiff’s invoices to defendant. The amount of prejudgment interest should be calculated at the rate of 9% per annum (see, Metropolitan Sav. Bank v Tuttle, 290 NY 497, 500, rearg denied 291 NY 634; Marine Midland Bank v 281 Groton Corp., 142 AD2d 941; see also, CPLR 5001 [a], [b]; 5004). Accordingly, the award of damages is modified to award plaintiff the sum of $41,713.47.
We have examined defendant’s other contention and find it to be without merit. (Appeal from Order and Judgment of Supreme Court, Erie County, Francis, J.—Summary Judgment.) Present—Callahan, A. P. J., Denman, Green, Pine and Davis, JJ.