The invention relates to a novel hemi-succinate salt form of (2S)-2-tert-butoxy-2-(4-(2,3-dihydropyrano[4,3,2-de]quinolin-7-yl)-2-methylquinolin-3-yl)acetic acid and a novel crystalline form thereof, methods for the preparation thereof, pharmaceutical compositions thereof and their use in the treatment of Human Immunodeficiency Virus (HIV) infection.