Capital gain

Sir/Madam, I need to get a clarity on the following case relationg to capital gain: Vacant land purchased on 18-07-2012 (2012-13) for Rs.12,24,000/- Cost of Improvement on 30.06.2015 for Rs.500000/- (Work completed in the same year itself ie., 2016-17) The said asset sold on 20.02.2017 for Rs.40,00,000/- In the given case, Cost of acquisition will qualify to indexation since it is a long term capital asset. My doubt is Will cost of improvement considered as short term or long term??