--- Net2/sys/user.h	2018/04/24 18:03:58	1.1
+++ Net2/sys/user.h	2018/04/24 18:16:13	1.1.1.2
@@ -30,9 +30,13 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	@(#)user.h	7.19 (Berkeley) 5/4/91
+ *	from: @(#)user.h	7.19 (Berkeley) 5/4/91
+ *	user.h,v 1.3 1993/05/20 16:23:45 cgd Exp
  */
 
+#ifndef _SYS_USER_H_
+#define _SYS_USER_H_
+
 #include <machine/pcb.h>
 #ifndef KERNEL
 /* stuff that *used* to be included by user.h, or is now needed */
@@ -88,3 +92,5 @@ struct	user {
 #define	u_sig	U_sig
 #define	u_code	U_code
 #endif /* KERNEL */
+
+#endif /* !_SYS_USER_H_ */