for _, part := range img.parts {
                dev := filepath.Join("/dev/mapper", part.loop)

                if part.fs == fsFat32 {
                        cmd := []string{"mkfs.vfat", "-F", "32", "-n", string(part.label)}

                        size, err := sectorSize(dev)
                        if err != nil {
                                return err
                        }

                        if size != "512" {
                                cmd = append(cmd, "-s", "1")
                        }

                        cmd = append(cmd, "-S", size, dev)

                        if out, err := exec.Command(cmd[0], cmd[1:]...).CombinedOutput(); err != nil {
                                return &ErrExec{command: cmd, output: out}
                        }
                } else {
                        cmd := []string{"mkfs.ext4", "-F", "-L", string(part.label), dev}
                        if out, err := exec.Command(cmd[0], cmd[1:]...).CombinedOutput(); err != nil {
                                return &ErrExec{command: cmd, output: out}
                        }
                }
        }