The use of at least one MXDZ polyamide, obtained from the polycondensation of meta-xylylenediamine (MXD), with a C6 to C18 aliphatic (Z) dicarboxylic acid, in particular C6 to C12, in a mixture including at least one aliphatic polyamide A obtained from the polycondensation of a unit selected from: a C6 to C12 lactam, a C6 to C12amino acid, and an XY unit obtained from the polycondensation of a C4 to C18, aliphatic diamine (X), especially C4 to C12, and a C6 to C18 aliphatic dicarboxylic acid (Y), especially C6 to C12, circular-section glass fibres and optionally at least one impact modifier and/or at least one additive, said at least one MXDZ polyamide and said mixture constituting a composition, and the MXDZ/A weight ratio being from 0.11 to 0.83, in particular from 0.11 to 0.66, to limit the warping of said composition during processing, in particular by injection or compression moulding.