This is not installed by autotools but software using CMake depends on it. In Arch they fixed this by running CMake manually and installing the extra file: https://bugs.archlinux.org/task/67604 https://gitlab.archlinux.org/archlinux/packaging/packages/fftw/-/blob/0fa56ea6f198f08c48325a46763e27913b2ee436/PKGBUILD#L99 Reproducible: Always