Carex firma is a species of sedge that grows in the mountains of southern and central Europe.

Carex firma forms thick cushions.

The larvae feed on Carex sempervirens and Carex firma.

In alpine locations P. alpina is often found growing with Carex firma (an alpine grass), Bistorta officinalis, Dryas octopetala, and Pedicularis rostratocapitata.

Carex firma was first described by Nicolaus Thomas Host in 1797, in his work Synopsis Plantarum in Austria provinciisque adjacentibus sponte crescentium.

Trochulus oreinos does not live in forests, but instead inhabits primarily boulders, screes and alpine grassland, especially alpine meadows with patchy vegetation coverage, dominated by the sedge species Carex firma, in the Northern Calcareous Alps.