The suit out of which this revision petition arises was for a sum of money said to be the excess rent which the petitioner had agreed to pay to the respondent in accordance with a rent chit executed by him. The agreement was that the petitioner should pay Rs. 9 per month as rent for the premises from 1st July, 1947, till 30th June, 1949, and vacate the premises thereafter. If, on the other hand, he continued to remain on the premises, a higher rent at the rate of Rs. 14 per mensem was to be paid. The present suit is for recovery of the difference in rent from 1st July, 1949 to 12th January, 1951, at the rate of Rs. 5 per mensem. The defendant contested the suit on the ground that the agreement was null and void and was against the provisions of the Madras Buildings (Lease and Rent Control) Act,. 1946, and therefore the agreement could not be enforced. There is a further contention that since the plaintiff had received without protest the rent at the rate of Rs. 9 per mensem even after 1st July, 1949, he had waived the claim for the increased rent. The lower Court rejected both these contentions and decreed the suit. The question for consideration is whether the agreement