CREW III, J.
In August 1996 petitioner, a retired State employee, received a check from the Department of Public Service for underpayment of wages during the course of his employment. By letter dated September 8, 1997, petitioner demanded interest on his back pay. On November 7, 1997, respondent denied petitioner's request for interest, prompting commencement of this CPLR article 78 proceeding on March 2, 1998. Respondent's subsequent motion to dismiss the petition as, inter alia, untimely was granted by Supreme Court and this appeal ensued.
We affirm. Even assuming, as petitioner contends, that this proceeding is one in the nature of mandamus to compel, he still cannot prevail. Although the applicable four-month Statute of Limitations indeed would not begin to run until the date petitioner's demand for interest was refused (see, Matter of De Milio v. Borghard, 55 N.Y.2d 216, 220), "[t]his does not mean [petitioner] can, by delay in making [such] demand, extend indefinitely the period during within which he is required to take action" (Austin v. Board of Higher Educ. of City of N.Y., 5 N.Y.2d 430, 442). "If such a delay is unreasonable, petitioner will be guilty of laches and his proceeding barred * * *" (Matter of Tumminia v. Coughlin, 182 A.D.2d 885, 886 [citation omitted]; see,Matter of Connell v. Town Bd. of Town of Wilmington, 113 A.D.2d 359, 364, affd 67 N.Y.2d 896). Here, the 13-month delay between petitioner's receipt of back pay and his demand for interest thereon is lengthy, unexplained and, in our view, unreasonable (see, Matter of Civil Serv. Empls. Assn. v. Board of Educ., Patchogue-Medford Union Free School Dist., 239 A.D.2d 415). The judgment dismissing the petition is, therefore, affirmed.
Cardona, P.J., Spain, Carpinello and Mugglin, JJ., concur.
ORDERED that the judgment is affirmed, without costs.