The invention relates to the use of a composition comprising at least one semi-crystalline copolyamide A/X1Y in which: —A is a repeat unit obtained from the polycondensation of at least one C6 to C12 lactam, or at least one repeat unit XY obtained from the polycondensation of at least one aliphatic C4 to C18 diamine (X), and of at least one aliphatic C6 to C18, in particular C6 to C12, dicarboxylic acid (Y), —X1Y is a repeat unit obtained from the polycondensation of a diamine (X1) chosen from an arylamine, a cycloaliphatic diamine and a branched aliphatic diamine and of at least one aliphatic dicarboxylic acid (Y) identical to that of the unit XY, the A/X1Y weight ratio being from 60/40 to 95/5, glass fibres having a circular cross section, and optionally at least one impact modifier and/or at least one additive, for limiting warping while at the same time maintaining the cycle time of the obtained composition suitable for processing thereof, in particular by injection moulding.