diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index eefc346df752bf696242c649b84f7be974b99e6e..b9dc1c4fc6c91c5284b777c782c3a13cb3c76977 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -460,6 +460,34 @@ int ip_fib_check_default(__be32 gw, struct net_device *dev)
 	return -1;
 }
 
+static size_t fib_nexthop_nlmsg_size(const struct fib_nh_common *nhc,
+				     bool skip_oif)
+{
+	size_t nhsize = 0;
+
+	switch (nhc->nhc_gw_family) {
+	case AF_INET:
+		nhsize += nla_total_size(4); /* RTA_GATEWAY */
+		break;
+	case AF_INET6:
+		nhsize += nla_total_size(sizeof(struct rtvia) +
+					 sizeof(struct in6_addr));
+		break;
+	}
+
+	if (!skip_oif && nhc->nhc_dev)
+		nhsize += nla_total_size(4); /* RTA_OIF */
+
+	if (nhc->nhc_lwtstate) {
+		/* RTA_ENCAP */
+		nhsize += lwtunnel_get_encap_size(nhc->nhc_lwtstate);
+		/* RTA_ENCAP_TYPE */
+		nhsize += nla_total_size(2);
+	}
+
+	return nhsize;
+}
+
 static inline size_t fib_nlmsg_size(struct fib_info *fi)
 {
 	size_t payload = NLMSG_ALIGN(sizeof(struct rtmsg))
@@ -477,32 +505,35 @@ static inline size_t fib_nlmsg_size(struct fib_info *fi)
 		payload += nla_total_size(4); /* RTA_NH_ID */
 
 	if (nhs) {
-		size_t nh_encapsize = 0;
-		/* Also handles the special case nhs == 1 */
-
-		/* each nexthop is packed in an attribute */
-		size_t nhsize = nla_total_size(sizeof(struct rtnexthop));
+		size_t mpsize = 0;
 		unsigned int i;
 
-		/* may contain flow and gateway attribute */
-		nhsize += 2 * nla_total_size(4);
-
-		/* grab encap info */
 		for (i = 0; i < fib_info_num_path(fi); i++) {
 			struct fib_nh_common *nhc = fib_info_nhc(fi, i);
+			size_t nhsize;
+
+			nhsize = fib_nexthop_nlmsg_size(nhc, nhs != 1);
 
-			if (nhc->nhc_lwtstate) {
-				/* RTA_ENCAP_TYPE */
-				nh_encapsize += lwtunnel_get_encap_size(
-						nhc->nhc_lwtstate);
-				/* RTA_ENCAP */
-				nh_encapsize +=  nla_total_size(2);
+			if (nhs != 1)
+				nhsize += NLA_ALIGN(sizeof(struct rtnexthop));
+
+#ifdef CONFIG_IP_ROUTE_CLASSID
+			if (nhc->nhc_family == AF_INET) {
+				struct fib_nh *nh;
+
+				nh = container_of(nhc, struct fib_nh, nh_common);
+				if (nh->nh_tclassid)
+					nhsize += nla_total_size(4);
 			}
+#endif
+			if (nhs == 1)
+				payload += nhsize;
+			else
+				mpsize += nhsize;
 		}
 
-		/* all nexthops are packed in a nested attribute */
-		payload += nla_total_size((nhs * nhsize) + nh_encapsize);
-
+		if (nhs != 1)
+			payload += nla_total_size(mpsize);
 	}
 
 	return payload;