Right now there isn't any pesofication law, there is a total restriction on buying dollars. However temporary rentals (furnished spaces rented for 6 months or less) are not bound by the "Ley de Alquileres". If you ask him to pesofy your contract and not make any mention of a dollar price, be prepared for him to substantially increase the rental price. You can't expect him to accept terms that are only advantageous to the renter. Just the fact that he is willing to accept pesos at all on a rental contract for a temporary rental is rare, so if I were you I would accept it as is. Good luck.