The metallicity of the progenitor star plays a crucial role in shaping the mass of a black hole. Our new study shows that this holds even in young star clusters. Intermediate-mass black holes and black holes with mass in the pair-instability gap (~60 – 150 Msun) form preferentially in metal-poor star clusters. The most massive binary black hole merger we form has a primary mass of ~90 Msun and a secondary mass o ~50 Msun.