This was broken by PR #70235 with commit f5ae5cac - freeglut: 3.0.0 -> 3.2.1 The in the newer freeglut version, the pkg-config file is called `glut.pc`, no longer `freeglut.pc`. Found in: https://github.com/NixOS/nixpkgs/pull/70235#issuecomment-567536852
f5ae5cac