The present invention relates to a process for producing a thermoplastic polyurethane, comprising the provision of a composition Z(W) comprising at least one carbodiimide selected from the group consisting of monomeric aliphatic carbodiimides, oligomeric aliphatic carbodiimides, polymeric aliphatic carbodiimides, monomeric aromatic carbodiimides, oligomeric aromatic carbodiimides and polymeric aromatic carbodiimides, and at least one ester selected from the group consisting of citric acid esters, acetyl citric acid esters, phthalic acid esters, benzoic acid esters, adipic acid esters, hydrogenated phthalic acid esters and phosphoric acid esters; and the subsequent addition of the composition Z(W) to a thermoplastic polyurethane or a reaction mixture for producing a thermoplastic polyurethane. Further, the present invention relates to a thermoplastic polyurethane obtainable or obtained by a process according to the invention and to the use of the composition Z(W) as plasticizer for thermoplastic polyurethanes. The present invention also relates to moldings comprising a thermoplastic polyurethane according to the invention.