diff --git a/ipv4/defs_darwin.go b/ipv4/defs_darwin.go
index e886802..9c68276 100644
--- a/ipv4/defs_darwin.go
+++ b/ipv4/defs_darwin.go
@@ -17,38 +17,10 @@
 import "C"
 
 const (
-	sysIP_OPTIONS     = C.IP_OPTIONS
-	sysIP_HDRINCL     = C.IP_HDRINCL
-	sysIP_TOS         = C.IP_TOS
-	sysIP_TTL         = C.IP_TTL
-	sysIP_RECVOPTS    = C.IP_RECVOPTS
-	sysIP_RECVRETOPTS = C.IP_RECVRETOPTS
 	sysIP_RECVDSTADDR = C.IP_RECVDSTADDR
-	sysIP_RETOPTS     = C.IP_RETOPTS
 	sysIP_RECVIF      = C.IP_RECVIF
-	sysIP_STRIPHDR    = C.IP_STRIPHDR
 	sysIP_RECVTTL     = C.IP_RECVTTL
-	sysIP_BOUND_IF    = C.IP_BOUND_IF
 	sysIP_PKTINFO     = C.IP_PKTINFO
-	sysIP_RECVPKTINFO = C.IP_RECVPKTINFO
-
-	sysIP_MULTICAST_IF           = C.IP_MULTICAST_IF
-	sysIP_MULTICAST_TTL          = C.IP_MULTICAST_TTL
-	sysIP_MULTICAST_LOOP         = C.IP_MULTICAST_LOOP
-	sysIP_ADD_MEMBERSHIP         = C.IP_ADD_MEMBERSHIP
-	sysIP_DROP_MEMBERSHIP        = C.IP_DROP_MEMBERSHIP
-	sysIP_MULTICAST_VIF          = C.IP_MULTICAST_VIF
-	sysIP_MULTICAST_IFINDEX      = C.IP_MULTICAST_IFINDEX
-	sysIP_ADD_SOURCE_MEMBERSHIP  = C.IP_ADD_SOURCE_MEMBERSHIP
-	sysIP_DROP_SOURCE_MEMBERSHIP = C.IP_DROP_SOURCE_MEMBERSHIP
-	sysIP_BLOCK_SOURCE           = C.IP_BLOCK_SOURCE
-	sysIP_UNBLOCK_SOURCE         = C.IP_UNBLOCK_SOURCE
-	sysMCAST_JOIN_GROUP          = C.MCAST_JOIN_GROUP
-	sysMCAST_LEAVE_GROUP         = C.MCAST_LEAVE_GROUP
-	sysMCAST_JOIN_SOURCE_GROUP   = C.MCAST_JOIN_SOURCE_GROUP
-	sysMCAST_LEAVE_SOURCE_GROUP  = C.MCAST_LEAVE_SOURCE_GROUP
-	sysMCAST_BLOCK_SOURCE        = C.MCAST_BLOCK_SOURCE
-	sysMCAST_UNBLOCK_SOURCE      = C.MCAST_UNBLOCK_SOURCE
 
 	sizeofSockaddrStorage = C.sizeof_struct_sockaddr_storage
 	sizeofSockaddrInet    = C.sizeof_struct_sockaddr_in
diff --git a/ipv4/sys_darwin.go b/ipv4/sys_darwin.go
index ac213c7..f6bf8ed 100644
--- a/ipv4/sys_darwin.go
+++ b/ipv4/sys_darwin.go
@@ -11,34 +11,36 @@
 
 	"golang.org/x/net/internal/iana"
 	"golang.org/x/net/internal/socket"
+
+	"golang.org/x/sys/unix"
 )
 
 var (
 	ctlOpts = [ctlMax]ctlOpt{
-		ctlTTL:        {sysIP_RECVTTL, 1, marshalTTL, parseTTL},
-		ctlDst:        {sysIP_RECVDSTADDR, net.IPv4len, marshalDst, parseDst},
-		ctlInterface:  {sysIP_RECVIF, syscall.SizeofSockaddrDatalink, marshalInterface, parseInterface},
-		ctlPacketInfo: {sysIP_PKTINFO, sizeofInetPktinfo, marshalPacketInfo, parsePacketInfo},
+		ctlTTL:        {unix.IP_RECVTTL, 1, marshalTTL, parseTTL},
+		ctlDst:        {unix.IP_RECVDSTADDR, net.IPv4len, marshalDst, parseDst},
+		ctlInterface:  {unix.IP_RECVIF, syscall.SizeofSockaddrDatalink, marshalInterface, parseInterface},
+		ctlPacketInfo: {unix.IP_PKTINFO, sizeofInetPktinfo, marshalPacketInfo, parsePacketInfo},
 	}
 
 	sockOpts = map[int]*sockOpt{
-		ssoTOS:                {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_TOS, Len: 4}},
-		ssoTTL:                {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_TTL, Len: 4}},
-		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_TTL, Len: 1}},
-		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_IF, Len: sizeofIPMreqn}, typ: ssoTypeIPMreqn},
-		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_MULTICAST_LOOP, Len: 4}},
-		ssoReceiveTTL:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVTTL, Len: 4}},
-		ssoReceiveDst:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVDSTADDR, Len: 4}},
-		ssoReceiveInterface:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVIF, Len: 4}},
-		ssoHeaderPrepend:      {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_HDRINCL, Len: 4}},
-		ssoStripHeader:        {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_STRIPHDR, Len: 4}},
-		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_JOIN_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
-		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_LEAVE_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
-		ssoJoinSourceGroup:    {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_JOIN_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoLeaveSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_LEAVE_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoBlockSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_BLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoUnblockSourceGroup: {Option: socket.Option{Level: iana.ProtocolIP, Name: sysMCAST_UNBLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
-		ssoPacketInfo:         {Option: socket.Option{Level: iana.ProtocolIP, Name: sysIP_RECVPKTINFO, Len: 4}},
+		ssoTOS:                {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_TOS, Len: 4}},
+		ssoTTL:                {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_TTL, Len: 4}},
+		ssoMulticastTTL:       {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_TTL, Len: 1}},
+		ssoMulticastInterface: {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_IF, Len: sizeofIPMreqn}, typ: ssoTypeIPMreqn},
+		ssoMulticastLoopback:  {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_MULTICAST_LOOP, Len: 4}},
+		ssoReceiveTTL:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVTTL, Len: 4}},
+		ssoReceiveDst:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVDSTADDR, Len: 4}},
+		ssoReceiveInterface:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVIF, Len: 4}},
+		ssoHeaderPrepend:      {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_HDRINCL, Len: 4}},
+		ssoStripHeader:        {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_STRIPHDR, Len: 4}},
+		ssoJoinGroup:          {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_JOIN_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
+		ssoLeaveGroup:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_LEAVE_GROUP, Len: sizeofGroupReq}, typ: ssoTypeGroupReq},
+		ssoJoinSourceGroup:    {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_JOIN_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoLeaveSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_LEAVE_SOURCE_GROUP, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoBlockSourceGroup:   {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_BLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoUnblockSourceGroup: {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.MCAST_UNBLOCK_SOURCE, Len: sizeofGroupSourceReq}, typ: ssoTypeGroupSourceReq},
+		ssoPacketInfo:         {Option: socket.Option{Level: iana.ProtocolIP, Name: unix.IP_RECVPKTINFO, Len: 4}},
 	}
 )
 
diff --git a/ipv4/zsys_darwin.go b/ipv4/zsys_darwin.go
index e05a251..345932b 100644
--- a/ipv4/zsys_darwin.go
+++ b/ipv4/zsys_darwin.go
@@ -4,38 +4,10 @@
 package ipv4
 
 const (
-	sysIP_OPTIONS     = 0x1
-	sysIP_HDRINCL     = 0x2
-	sysIP_TOS         = 0x3
-	sysIP_TTL         = 0x4
-	sysIP_RECVOPTS    = 0x5
-	sysIP_RECVRETOPTS = 0x6
 	sysIP_RECVDSTADDR = 0x7
-	sysIP_RETOPTS     = 0x8
 	sysIP_RECVIF      = 0x14
-	sysIP_STRIPHDR    = 0x17
 	sysIP_RECVTTL     = 0x18
-	sysIP_BOUND_IF    = 0x19
 	sysIP_PKTINFO     = 0x1a
-	sysIP_RECVPKTINFO = 0x1a
-
-	sysIP_MULTICAST_IF           = 0x9
-	sysIP_MULTICAST_TTL          = 0xa
-	sysIP_MULTICAST_LOOP         = 0xb
-	sysIP_ADD_MEMBERSHIP         = 0xc
-	sysIP_DROP_MEMBERSHIP        = 0xd
-	sysIP_MULTICAST_VIF          = 0xe
-	sysIP_MULTICAST_IFINDEX      = 0x42
-	sysIP_ADD_SOURCE_MEMBERSHIP  = 0x46
-	sysIP_DROP_SOURCE_MEMBERSHIP = 0x47
-	sysIP_BLOCK_SOURCE           = 0x48
-	sysIP_UNBLOCK_SOURCE         = 0x49
-	sysMCAST_JOIN_GROUP          = 0x50
-	sysMCAST_LEAVE_GROUP         = 0x51
-	sysMCAST_JOIN_SOURCE_GROUP   = 0x52
-	sysMCAST_LEAVE_SOURCE_GROUP  = 0x53
-	sysMCAST_BLOCK_SOURCE        = 0x54
-	sysMCAST_UNBLOCK_SOURCE      = 0x55
 
 	sizeofSockaddrStorage = 0x80
 	sizeofSockaddrInet    = 0x10