The present invention relates to a composition comprising polypropylene, polyethylene and a compatibiliser, wherein said compatibiliser is a block copolymer comprising a polypropylene block and a polyester block, said polyester being a non-aromatic polyester and having an average M/E ratio of at least 10, wherein M is the number of backbone carbon atoms in the polyester not including the carbonyl carbons and E is the number of ester groups in the polyester.