diff --git a/sys/net/if_stf.c b/sys/net/if_stf.c
--- a/sys/net/if_stf.c
+++ b/sys/net/if_stf.c
@@ -318,22 +318,22 @@
 
 	sc = (struct stf_softc *)arg;
 	if (sc == NULL)
-		return 0;
+		return (0);
 
 	if ((STF2IFP(sc)->if_flags & IFF_UP) == 0)
-		return 0;
+		return (0);
 
 	/* IFF_LINK0 means "no decapsulation" */
 	if ((STF2IFP(sc)->if_flags & IFF_LINK0) != 0)
-		return 0;
+		return (0);
 
 	if (proto != IPPROTO_IPV6)
-		return 0;
+		return (0);
 
 	m_copydata(m, 0, sizeof(ip), (caddr_t)&ip);
 
 	if (ip.ip_v != 4)
-		return 0;
+		return (0);
 
 	if (stf_getsrcifa6(STF2IFP(sc), &addr6, &mask6) != 0)
 		return (0);
@@ -344,7 +344,7 @@
 	 * success on: dst = 10.1.1.1, ia6->ia_addr = 2002:0a01:0101:...
 	 */
 	if (bcmp(GET_V4(&addr6), &ip.ip_dst, sizeof(ip.ip_dst)) != 0)
-		return 0;
+		return (0);
 
 	/*
 	 * check if IPv4 src matches the IPv4 address derived from the
@@ -359,10 +359,10 @@
 	b = ip.ip_src;
 	b.s_addr &= mask.s_addr;
 	if (a.s_addr != b.s_addr)
-		return 0;
+		return (0);
 
 	/* stf interface makes single side match only */
-	return 32;
+	return (32);
 }
 
 static int
@@ -429,7 +429,7 @@
 	if ((ifp->if_flags & IFF_UP) == 0) {
 		m_freem(m);
 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
-		return ENETDOWN;
+		return (ENETDOWN);
 	}
 
 	/*
@@ -440,14 +440,14 @@
 	if (stf_getsrcifa6(ifp, &addr6, &mask6) != 0) {
 		m_freem(m);
 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
-		return ENETDOWN;
+		return (ENETDOWN);
 	}
 
 	if (m->m_len < sizeof(*ip6)) {
 		m = m_pullup(m, sizeof(*ip6));
 		if (!m) {
 			if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
-			return ENOBUFS;
+			return (ENOBUFS);
 		}
 	}
 	ip6 = mtod(m, struct ip6_hdr *);
@@ -465,7 +465,7 @@
 	else {
 		m_freem(m);
 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
-		return ENETUNREACH;
+		return (ENETUNREACH);
 	}
 	bcopy(ptr, &in4, sizeof(in4));
 
@@ -484,7 +484,7 @@
 	M_PREPEND(m, sizeof(struct ip), M_NOWAIT);
 	if (m == NULL) {
 		if_inc_counter(ifp, IFCOUNTER_OERRORS, 1);
-		return ENOBUFS;
+		return (ENOBUFS);
 	}
 	ip = mtod(m, struct ip *);
 
@@ -504,7 +504,7 @@
 	if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
 	error = ip_output(m, NULL, NULL, 0, NULL, NULL);
 
-	return error;
+	return (error);
 }
 
 static int
@@ -518,9 +518,9 @@
 	    (ntohl(in->s_addr) & 0xff000000) >> 24 == 10 ||
 	    (ntohl(in->s_addr) & 0xfff00000) >> 16 == 172 * 256 + 16 ||
 	    (ntohl(in->s_addr) & 0xffff0000) >> 16 == 192 * 256 + 168))
-		return 1;
+		return (1);
 
-	return 0;
+	return (0);
 }
 
 static int
@@ -533,10 +533,10 @@
 	 * 224.0.0.0/4 0.0.0.0/8 127.0.0.0/8 255.0.0.0/8
 	 */
 	if (IN_MULTICAST(ntohl(in->s_addr)))
-		return -1;
+		return (-1);
 	switch ((ntohl(in->s_addr) & 0xff000000) >> 24) {
 	case 0: case 127: case 255:
-		return -1;
+		return (-1);
 	}
 
 	/*
@@ -544,7 +544,7 @@
 	 * (requirement from RFC3056 section 2 1st paragraph)
 	 */
 	if (isrfc1918addr(in))
-		return -1;
+		return (-1);
 
 	/*
 	 * reject packets with broadcast
@@ -553,7 +553,7 @@
 		if ((ia4->ia_ifa.ifa_ifp->if_flags & IFF_BROADCAST) == 0)
 			continue;
 		if (in->s_addr == ia4->ia_broadaddr.sin_addr.s_addr) {
-			return -1;
+			return (-1);
 		}
 	}
 
@@ -572,7 +572,7 @@
 			return (-1);
 	}
 
-	return 0;
+	return (0);
 }
 
 static int
@@ -584,7 +584,7 @@
 	if (IN6_IS_ADDR_6TO4(in6)) {
 		struct in_addr in4;
 		bcopy(GET_V4(in6), &in4, sizeof(in4));
-		return stf_checkaddr4(sc, &in4, inifp);
+		return (stf_checkaddr4(sc, &in4, inifp));
 	}
 
 	/*
@@ -594,9 +594,9 @@
 	 * (2) to be safe against future ip6_input change.
 	 */
 	if (IN6_IS_ADDR_V4COMPAT(in6) || IN6_IS_ADDR_V4MAPPED(in6))
-		return -1;
+		return (-1);
 
-	return 0;
+	return (0);
 }
 
 static int
@@ -750,5 +750,5 @@
 		break;
 	}
 
-	return error;
+	return (error);
 }