This invention relates a wax inhibitor for hydrocarbon oils comprising an esterified copolymer having repeating structural units derived from an esterified ethylenically unsaturated dicarboxylic acid and α-olefins having at least 18 carbon atoms, whereof at least 3 mol-% of the α-olefins have 30 or more carbon atoms, and wherein the ethylenically unsaturated dicarboxylic acid has been esterified with a mixture of alcohols comprising

i) 70 to 97 mol-% of a saturated fatty alcohol having 18 to 24 carbon atoms and
ii) 3 to 30 mol-% of an unsaturated alcohol having 16 to 24 carbon atoms.