Uncompressed aarch64 and riscv64 kernels have a different startpoint than x86. Example output from ukify: aarch64: NotImplementedError: unknown file format (starts with b'MZ@\xfa') riscv64: NotImplementedError: unknown file format (starts with b'MZo\x10') Add check for (b'MZ') to catch both in one call. Fix: https://github.com/systemd/systemd/issues/26923