How can i prevent my son from licking the walls?

Ok so my son is 5 months and we are renting this house for about 6 more months well this house has more than 100 years and well the landlord told us that we should be careful because of the lead and that as long as the baby dont lick them he should be ok ..we rented here in desperation because we had nowhere to go and we had no other choice we cannot leave until the contract has ended which is in 6 months or else we have to pay him the 6 months of renting for breaking the contract which would be 6,000 .so ofcourse we dont have that kind of money my son will be 11 months when the contract ends but hes gona start trying to walk by then right i know thats the age where hes gonna be everywhere and graving everything and putting everything in his mouth ..what can i do ??