diff --git a/lib/libstand/bootp.c b/lib/libstand/bootp.c
index 35ccf7a74400..c440c982c54d 100644
--- a/lib/libstand/bootp.c
+++ b/lib/libstand/bootp.c
@@ -37,6 +37,7 @@
  * SUCH DAMAGE.
  *
  * @(#) Header: bootp.c,v 1.4 93/09/11 03:13:51 leres Exp  (LBL)
+ * $FreeBSD$
  */
 
 #include <sys/types.h>
@@ -80,8 +81,9 @@ struct in_addr dhcp_serverip;
 
 /* Fetch required bootp infomation */
 void
-bootp(sock)
+bootp(sock, flag)
 	int sock;
+	int flag;
 {
 	struct iodesc *d;
 	register struct bootp *bp;
@@ -124,7 +126,19 @@ bootp(sock)
 	bp->bp_vend[4] = TAG_DHCP_MSGTYPE;
 	bp->bp_vend[5] = 1;
 	bp->bp_vend[6] = DHCPDISCOVER;
-	bp->bp_vend[7] = TAG_END;
+
+	/*
+	 * If we are booting from PXE, we want to send the string
+	 * 'PXEClient' to the DHCP server so you have the option of
+	 * only responding to PXE aware dhcp requests.
+	 */
+	if (flag & BOOTP_PXE) {
+		bp->bp_vend[7] = TAG_CLASSID;
+		bp->bp_vend[8] = 9;
+		bcopy("PXEClient", &bp->bp_vend[9], 9);
+		bp->bp_vend[18] = TAG_END;
+	} else
+		bp->bp_vend[7] = TAG_END;
 #else
 	bp->bp_vend[4] = TAG_END;
 #endif
@@ -161,7 +175,13 @@ bootp(sock)
 		bp->bp_vend[20] = 4;
 		leasetime = htonl(300);
 		bcopy(&leasetime, &bp->bp_vend[21], 4);
-		bp->bp_vend[25] = TAG_END;
+		if (flag & BOOTP_PXE) {
+			bp->bp_vend[25] = TAG_CLASSID;
+			bp->bp_vend[26] = 9;
+			bcopy("PXEClient", &bp->bp_vend[27], 9);
+			bp->bp_vend[36] = TAG_END;
+		} else
+			bp->bp_vend[25] = TAG_END;
 
 		expected_dhcpmsgtype = DHCPACK;
 
diff --git a/lib/libstand/bootp.h b/lib/libstand/bootp.h
index 7435e3cdbbb0..ed9101f3ea89 100644
--- a/lib/libstand/bootp.h
+++ b/lib/libstand/bootp.h
@@ -18,6 +18,8 @@
  * University.  Carnegie Mellon makes no representations about the
  * suitability of this software for any purpose.  It is provided "as is"
  * without express or implied warranty.
+ *
+ * $FreeBSD$
  */
 
 
@@ -117,6 +119,12 @@ struct bootp {
 #define DHCPRELEASE 7
 #endif
 
+/*
+ * bootp flags
+ */
+#define	BOOTP_NONE		0x0000		/* No flags */
+#define	BOOTP_PXE		0x0001		/* Booting from PXE. */
+
 /*
  * "vendor" data permitted for CMU bootp clients.
  */
diff --git a/lib/libstand/net.h b/lib/libstand/net.h
index 47ff0a0d2e20..24534afcaaca 100644
--- a/lib/libstand/net.h
+++ b/lib/libstand/net.h
@@ -114,7 +114,7 @@ ssize_t	sendrecv(struct iodesc *,
 			void *, size_t);
 
 /* bootp/DHCP */
-void	bootp(int);
+void	bootp(int, int);
 
 /* Utilities: */
 char	*ether_sprintf(u_char *);
diff --git a/sys/boot/common/dev_net.c b/sys/boot/common/dev_net.c
index c88dae708d25..884366f1e1ee 100644
--- a/sys/boot/common/dev_net.c
+++ b/sys/boot/common/dev_net.c
@@ -68,6 +68,7 @@
 #include <string.h>
 #include <net.h>
 #include <netif.h>
+#include <bootp.h>
 #include <bootparam.h>
 
 #include "dev_net.h"
@@ -217,7 +218,7 @@ net_getparams(sock)
      * use RARP and RPC/bootparam (the Sun way) to get them.
      */
     if (try_bootp)
-	bootp(sock);
+	bootp(sock, BOOTP_NONE);
     if (myip.s_addr != 0)
 	goto exit;
     if (debug)
diff --git a/sys/boot/i386/libi386/pxe.c b/sys/boot/i386/libi386/pxe.c
index fa3a4f229fc3..0357cbe31309 100644
--- a/sys/boot/i386/libi386/pxe.c
+++ b/sys/boot/i386/libi386/pxe.c
@@ -41,6 +41,7 @@
 #include <net.h>
 #include <netif.h>
 
+#include <bootp.h>
 #include <bootstrap.h>
 #include "btxv86.h"
 #include "pxe.h"
@@ -276,7 +277,7 @@ pxe_open(struct open_file *f, ...)
 		 * the proper information, fall back to the server
 		 * which brought us to life and a default rootpath.
 		 */
-		bootp(pxe_sock);
+		bootp(pxe_sock, BOOTP_PXE);
 		if (rootip.s_addr == 0)
 			rootip.s_addr = bootplayer.sip;
 		if (!rootpath[1])
diff --git a/sys/boot/i386/libi386/pxe.h b/sys/boot/i386/libi386/pxe.h
index c6bc4d0bc00a..3c9f2ff09f9b 100644
--- a/sys/boot/i386/libi386/pxe.h
+++ b/sys/boot/i386/libi386/pxe.h
@@ -498,7 +498,9 @@ typedef struct {
 		uint8_t		d[BOOTP_DHCPVEND];	/* raw array of vendor/dhcp options */
 		struct {
 			uint8_t		magic[4];	/* DHCP magic cookie */
+#			ifndef		VM_RFC1048
 #			define		VM_RFC1048	0x63825363L	/* ? */
+#			endif
 			uint32_t	flags;		/* bootp flags/opcodes */
 			uint8_t		pad[56];	/* I don't think intel knows what a
 							   union does... */