We have investigated the role of carbon, boron and zirconium on the hot cracking susceptibility of a polycrystalline nickel-based superalloy produced by laser powder bed fusion. The segregation of grain boundary solutes was studied in the as-built condition and compared with that after heat treatment. Transmission electron microscopy (TEM) and atom probe tomography (APT) revealed that there is an alteration of the solutes segregating at grain boundaries before and after heat treatment. These observations have a substantial impact on the design of crack-free additively manufactured superalloys.