diff --git a/sys/net/if_loop.c b/sys/net/if_loop.c
index dc297fc524e..f1a017b09d0 100644
--- a/sys/net/if_loop.c
+++ b/sys/net/if_loop.c
@@ -94,6 +94,11 @@
 #define LOMTU	16384
 #endif
 
+#define	LO_CSUM_FEATURES	(CSUM_IP | CSUM_TCP | CSUM_UDP | CSUM_SCTP)
+#define	LO_CSUM_SET		(CSUM_DATA_VALID | CSUM_PSEUDO_HDR | \
+				    CSUM_IP_CHECKED | CSUM_IP_VALID | \
+				    CSUM_SCTP_VALID)
+
 int		loioctl(struct ifnet *, u_long, caddr_t);
 static void	lortrequest(int, struct rtentry *, struct rt_addrinfo *);
 int		looutput(struct ifnet *ifp, struct mbuf *m,
@@ -139,7 +144,7 @@ lo_clone_create(struct if_clone *ifc, int unit, caddr_t params)
 	ifp->if_output = looutput;
 	ifp->if_snd.ifq_maxlen = ifqmaxlen;
 	ifp->if_capabilities = ifp->if_capenable = IFCAP_HWCSUM;
-	ifp->if_hwassist = CSUM_IP | CSUM_TCP | CSUM_UDP;
+	ifp->if_hwassist = LO_CSUM_FEATURES;
 	if_attach(ifp);
 	bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
 	if (V_loif == NULL)
@@ -216,11 +221,9 @@ looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
 	case AF_INET:
 		if (ifp->if_capenable & IFCAP_RXCSUM) {
 			m->m_pkthdr.csum_data = 0xffff;
-			m->m_pkthdr.csum_flags = CSUM_DATA_VALID |
-			    CSUM_PSEUDO_HDR | CSUM_IP_CHECKED |
-			    CSUM_IP_VALID | CSUM_SCTP_VALID;
+			m->m_pkthdr.csum_flags = LO_CSUM_SET;
 		}
-		m->m_pkthdr.csum_flags &= ~(CSUM_IP | CSUM_TCP | CSUM_UDP);
+		m->m_pkthdr.csum_flags &= ~LO_CSUM_FEATURES;
 	case AF_INET6:
 	case AF_IPX:
 	case AF_APPLETALK:
@@ -407,7 +410,7 @@ loioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
 		if ((mask & IFCAP_TXCSUM) != 0)
 			ifp->if_capenable ^= IFCAP_TXCSUM;
 		if (ifp->if_capenable & IFCAP_TXCSUM)
-			ifp->if_hwassist = CSUM_IP | CSUM_TCP | CSUM_UDP;
+			ifp->if_hwassist = LO_CSUM_FEATURES;
 		else
 			ifp->if_hwassist = 0;
 		break;