The present invention relates to the use of a copolymer comprising, in polymerized form, (a) from 80 to 99.9 mol %, based on the total amount of the monomers polymerized to prepare the copolymer, of at least one monomer A which in each case comprises a heterocycle having at least 1 nitrogen atom and composed of from 3 to 10 ring members and a C.sub.2-C.sub.6-alkenyl group bonded to a carbon or nitrogen ring atom of the heterocycle; and (b) from 0.1 to 20 mol %, based on the total amount of the monomers polymerized to prepare the copolymer, of at least one monomer B copolymerizable with monomer A, said monomer B having a monoethylenically unsaturated double bond and also a linear or branched poly-C.sub.2-C.sub.4-alkylene oxide group having on average from 4 to 500 C.sub.2-C.sub.4-alkylene oxide units, in liquid and in solid detergent formulations. In addition, the invention relates to a process for preparing such a copolymer, and also to a liquid or solid detergent formulation comprising at least one such copolymer.