diff --git a/src/include/gpxe/dhcp.h b/src/include/gpxe/dhcp.h
index e35b7eab..71c6c14a 100644
--- a/src/include/gpxe/dhcp.h
+++ b/src/include/gpxe/dhcp.h
@@ -23,7 +23,9 @@ struct dhcp_packet {
 	uint8_t op;
 	/** Hardware address type
 	 *
-	 * This is an ARPHRD_XXX constant.
+	 * This is an ARPHRD_XXX constant.  Note that ARPHRD_XXX
+	 * constants are nominally 16 bits wide; this could be
+	 * considered to be a bug in the BOOTP/DHCP specification.
 	 */
 	uint8_t htype;
 	/** Hardware address length */
@@ -274,6 +276,14 @@ struct dhcp_option_block {
 	signed int priority;
 };
 
+/** A DHCP session */
+struct dhcp_session {
+	/** Network device being configured */
+	struct net_device *netdev;
+	/** Transaction ID, in network-endian order */
+	uint32_t xid;
+};
+
 extern unsigned long dhcp_num_option ( struct dhcp_option *option );
 extern struct dhcp_option *
 find_dhcp_option ( struct dhcp_option_block *options, unsigned int tag );
diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c
index 1523e404..7e9af09f 100644
--- a/src/net/udp/dhcp.c
+++ b/src/net/udp/dhcp.c
@@ -29,11 +29,6 @@
  *
  */
 
-struct dhcp_session {
-	struct net_device *netdev;
-	uint32_t xid;
-};
-
 /** DHCP operation types
  *
  * This table maps from DHCP message types (i.e. values of the @c
@@ -186,7 +181,7 @@ size_t dhcp_assemble ( struct dhcp_session *dhcp, void *data,
 	dhcppkt->op = dhcp_op[dhcp_message_type];
 
 	/* Fill in NIC details */
-	dhcppkt->htype = dhcp->netdev->ll_protocol->ll_proto;
+	dhcppkt->htype = ntohs ( dhcp->netdev->ll_protocol->ll_proto );
 	dhcppkt->hlen = dhcp->netdev->ll_protocol->ll_addr_len;
 	memcpy ( dhcppkt->chaddr, dhcp->netdev->ll_addr, dhcppkt->hlen );