#include <fcntl.h>
#include <sys/socket.h>
#include <sys/stat.h>
+#include <stddef.h>
#include <dbus/dbus.h>
zero(msghdr);
msghdr.msg_name = &sockaddr;
- msghdr.msg_namelen = sizeof(sa_family_t) + 1 + sizeof("/org/freedesktop/systemd1/shutdownd") - 1;
+ msghdr.msg_namelen = offsetof(struct sockaddr_un, sun_path) + 1 + sizeof("/org/freedesktop/systemd1/shutdownd") - 1;
msghdr.msg_iov = &iovec;
msghdr.msg_iovlen = 1;