diff --git a/sys/netpfil/ipfw/ip_fw2.c b/sys/netpfil/ipfw/ip_fw2.c
--- a/sys/netpfil/ipfw/ip_fw2.c
+++ b/sys/netpfil/ipfw/ip_fw2.c
@@ -2064,11 +2064,9 @@
 					else if (vidx == 6 /* dscp */) {
 						if (is_ipv4)
 							key = ip->ip_tos >> 2;
-						else {
-							key = args->f_id.flow_id6;
-							key = (key & 0x0f) << 2 |
-							    (key & 0xf000) >> 14;
-						}
+						else
+							key = IPV6_DSCP(
+							    (struct ip6_hdr *)ip) >> 2;
 						key &= 0x3f;
 					} else if (vidx == 2 /* dst-port */ ||
 					    vidx == 3 /* src-port */) {
@@ -2328,11 +2326,9 @@
 				if (is_ipv4)
 					x = ip->ip_tos >> 2;
 				else if (is_ipv6) {
-					uint8_t *v;
-					v = &((struct ip6_hdr *)ip)->ip6_vfc;
-					x = (*v & 0x0F) << 2;
-					v++;
-					x |= *v >> 6;
+					x = IPV6_DSCP(
+					    (struct ip6_hdr *)ip) >> 2;
+					x &= 0x3f;
 				} else
 					break;
 
@@ -3139,12 +3135,13 @@
 					ip->ip_sum = cksum_adjust(ip->ip_sum,
 					    old, *(uint16_t *)ip);
 				} else if (is_ipv6) {
-					uint8_t *v;
+					/* update cached value */
+					args->f_id.flow_id6 =
+					    ntohl(*(uint32_t *)ip) & ~0x0FC00000;
+					args->f_id.flow_id6 |= code << 22;
 
-					v = &((struct ip6_hdr *)ip)->ip6_vfc;
-					*v = (*v & 0xF0) | (code >> 2);
-					v++;
-					*v = (*v & 0x3F) | ((code & 0x03) << 6);
+					*((uint32_t *)ip) =
+					    htonl(args->f_id.flow_id6);
 				} else
 					break;
 
diff --git a/sys/netpfil/ipfw/ip_fw_log.c b/sys/netpfil/ipfw/ip_fw_log.c
--- a/sys/netpfil/ipfw/ip_fw_log.c
+++ b/sys/netpfil/ipfw/ip_fw_log.c
@@ -156,8 +156,7 @@
 				altq->qid);
 			cmd += F_LEN(cmd);
 		}
-		if (cmd->opcode == O_PROB || cmd->opcode == O_TAG ||
-		    cmd->opcode == O_SETDSCP)
+		if (cmd->opcode == O_PROB || cmd->opcode == O_TAG)
 			cmd += F_LEN(cmd);
 
 		action = action2;
@@ -202,6 +201,10 @@
 			snprintf(SNPARGS(action2, 0), "Tee %d",
 				TARG(cmd->arg1, divert));
 			break;
+		case O_SETDSCP:
+			snprintf(SNPARGS(action2, 0), "SetDscp %d",
+				TARG(cmd->arg1, dscp) & 0x3F);
+			break;
 		case O_SETFIB:
 			snprintf(SNPARGS(action2, 0), "SetFib %d",
 				TARG(cmd->arg1, fib) & 0x7FFF);