A support arrangement for a machine portal includes a lightweight support structure and a row of base segments supporting at least one guide rail of a linear drive on the support structure. Both the base segments and the guide rail exhibit different thermal expansion behavior from the support structure. The base segments are fixed at a distance from their edges by fixing screws to respective fastening members extending into the support structure. The base segments define at least one step on which they support the guide rail with a positive fit. The guide rail is fixed to the support structure by at least one expansion screw. The support arrangement maintains precise alignment of the guide rail while accommodating differing thermal expansions between the rail, base segments and support structure.