diff --git a/prog/checksum.go b/prog/checksum.go
index 3806c59e..9df541dc 100644
--- a/prog/checksum.go
+++ b/prog/checksum.go
@@ -4,6 +4,7 @@
 package prog
 
 import (
+	"encoding/binary"
 	"fmt"
 	"unsafe"
 
@@ -90,7 +91,7 @@ func storeByBitmask64(addr *uint64, value uint64, bfOff uint64, bfLen uint64) {
 	}
 }
 
-func encodeStruct(arg *Arg, pid int) []byte {
+func encodeArg(arg *Arg, pid int) []byte {
 	bytes := make([]byte, arg.Size())
 	foreachSubargOffset(arg, func(arg *Arg, offset uintptr) {
 		switch arg.Kind {
@@ -120,38 +121,96 @@ func encodeStruct(arg *Arg, pid int) []byte {
 	return bytes
 }
 
-func calcChecksumIPv4(arg *Arg, pid int) (*Arg, *Arg) {
-	var csumField *Arg
+func getFieldByName(arg *Arg, name string) *Arg {
 	for _, field := range arg.Inner {
-		if _, ok := field.Type.(*sys.CsumType); ok {
-			csumField = field
-			break
+		if field.Type.FieldName() == name {
+			return field
 		}
 	}
-	if csumField == nil {
-		panic(fmt.Sprintf("failed to find csum field in %v", arg.Type.Name()))
+	panic(fmt.Sprintf("failed to find %v field in %v", name, arg.Type.Name()))
+}
+
+func calcChecksumIPv4(arg *Arg, pid int) (*Arg, *Arg) {
+	csumField := getFieldByName(arg, "csum")
+	if typ, ok := csumField.Type.(*sys.CsumType); !ok {
+		panic(fmt.Sprintf("checksum field has bad type %v, arg: %+v", csumField.Type, csumField))
+	} else if typ.Kind != sys.CsumIPv4 {
+		panic(fmt.Sprintf("checksum field has bad kind %v, arg: %+v", typ.Kind, csumField))
 	}
 	if csumField.Value(pid) != 0 {
 		panic(fmt.Sprintf("checksum field has nonzero value %v, arg: %+v", csumField.Value(pid), csumField))
 	}
-	bytes := encodeStruct(arg, pid)
+	bytes := encodeArg(arg, pid)
 	csum := ipChecksum(bytes)
 	newCsumField := *csumField
 	newCsumField.Val = uintptr(csum)
 	return csumField, &newCsumField
 }
 
+func extractHeaderParamsIPv4(arg *Arg) (*Arg, *Arg, *Arg) {
+	srcAddr := getFieldByName(arg, "src_ip")
+	if srcAddr.Size() != 4 {
+		panic(fmt.Sprintf("src_ip field in %v must be 4 bytes", arg.Type.Name()))
+	}
+	dstAddr := getFieldByName(arg, "dst_ip")
+	if dstAddr.Size() != 4 {
+		panic(fmt.Sprintf("dst_ip field in %v must be 4 bytes", arg.Type.Name()))
+	}
+	protocol := getFieldByName(arg, "protocol")
+	if protocol.Size() != 1 {
+		panic(fmt.Sprintf("protocol field in %v must be 1 byte", arg.Type.Name()))
+	}
+	return srcAddr, dstAddr, protocol
+}
+
+func calcChecksumTCP(tcpPacket, srcAddr, dstAddr, protocol *Arg, pid int) (*Arg, *Arg) {
+	tcpHeaderField := getFieldByName(tcpPacket, "header")
+	csumField := getFieldByName(tcpHeaderField, "csum")
+	if typ, ok := csumField.Type.(*sys.CsumType); !ok {
+		panic(fmt.Sprintf("checksum field has bad type %v, arg: %+v", csumField.Type, csumField))
+	} else if typ.Kind != sys.CsumTCP {
+		panic(fmt.Sprintf("checksum field has bad kind %v, arg: %+v", typ.Kind, csumField))
+	}
+
+	var csum IPChecksum
+	csum.Update(encodeArg(srcAddr, pid))
+	csum.Update(encodeArg(dstAddr, pid))
+	csum.Update([]byte{0, byte(protocol.Value(pid))})
+	length := []byte{0, 0}
+	binary.BigEndian.PutUint16(length, uint16(tcpPacket.Size()))
+	csum.Update(length)
+	csum.Update(encodeArg(tcpPacket, pid))
+
+	newCsumField := *csumField
+	newCsumField.Val = uintptr(csum.Digest())
+	return csumField, &newCsumField
+}
+
 func calcChecksumsCall(c *Call, pid int) map[*Arg]*Arg {
-	var m map[*Arg]*Arg
+	var csumMap map[*Arg]*Arg
+	ipv4HeaderParsed := false
+	var ipv4SrcAddr *Arg
+	var ipv4DstAddr *Arg
+	var ipv4Protocol *Arg
 	foreachArgArray(&c.Args, nil, func(arg, base *Arg, _ *[]*Arg) {
-		// syz_csum_ipv4 struct is used in tests
-		if arg.Type.Name() == "ipv4_header" || arg.Type.Name() == "syz_csum_ipv4" {
-			if m == nil {
-				m = make(map[*Arg]*Arg)
+		// syz_csum_ipv4_header struct is used in tests
+		if arg.Type.Name() == "ipv4_header" || arg.Type.Name() == "syz_csum_ipv4_header" {
+			if csumMap == nil {
+				csumMap = make(map[*Arg]*Arg)
 			}
-			k, v := calcChecksumIPv4(arg, pid)
-			m[k] = v
+			csumField, newCsumField := calcChecksumIPv4(arg, pid)
+			csumMap[csumField] = newCsumField
+			ipv4SrcAddr, ipv4DstAddr, ipv4Protocol = extractHeaderParamsIPv4(arg)
+			ipv4HeaderParsed = true
+		}
+		// syz_csum_tcp_packet struct is used in tests
+		if arg.Type.Name() == "tcp_packet" || arg.Type.Name() == "syz_csum_tcp_packet" {
+			if !ipv4HeaderParsed {
+				panic("tcp_packet is being parsed before ipv4_header")
+			}
+			csumField, newCsumField := calcChecksumTCP(arg, ipv4SrcAddr, ipv4DstAddr, ipv4Protocol, pid)
+			csumMap[csumField] = newCsumField
 		}
 	})
-	return m
+	return csumMap
 }
diff --git a/prog/checksum_test.go b/prog/checksum_test.go
index bade7f72..56561d4e 100644
--- a/prog/checksum_test.go
+++ b/prog/checksum_test.go
@@ -6,6 +6,8 @@ package prog
 import (
 	"bytes"
 	"testing"
+
+	"github.com/google/syzkaller/sys"
 )
 
 func TestChecksumIP(t *testing.T) {
@@ -53,6 +55,10 @@ func TestChecksumIP(t *testing.T) {
 			"\x00\x00\x42\x00\x00\x43\x44\x00\x00\x00\x45\x00\x00\x00\xba\xaa\xbb\xcc\xdd",
 			0xe143,
 		},
+		{
+			"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x04\x00\x00\xab\xcd",
+			0x542e,
+		},
 	}
 
 	for _, test := range tests {
@@ -102,7 +108,7 @@ func TestChecksumEncode(t *testing.T) {
 		if err != nil {
 			t.Fatalf("failed to deserialize prog %v: %v", test.prog, err)
 		}
-		encoded := encodeStruct(p.Calls[0].Args[0].Res, 0)
+		encoded := encodeArg(p.Calls[0].Args[0].Res, 0)
 		if !bytes.Equal(encoded, []byte(test.encoded)) {
 			t.Fatalf("incorrect encoding for prog #%v, got: %+v, want: %+v", i, encoded, []byte(test.encoded))
 		}
@@ -115,7 +121,7 @@ func TestChecksumIPv4Calc(t *testing.T) {
 		csum uint16
 	}{
 		{
-			"syz_test$csum_ipv4(&(0x7f0000000000)={0x0, {0x42, 0x43, [0x44, 0x45], 0xa, 0xb, \"aabbccdd\"}})",
+			"syz_test$csum_ipv4(&(0x7f0000000000)={0x0, {0x42, 0x43, [0x44, 0x45], 0xa, 0xb, \"aabbccdd\"}, 0x0, 0x0, 0x0})",
 			0xe143,
 		},
 	}
@@ -133,6 +139,37 @@ func TestChecksumIPv4Calc(t *testing.T) {
 	}
 }
 
+func TestChecksumTCPCalc(t *testing.T) {
+	tests := []struct {
+		prog string
+		csum uint16
+	}{
+		{
+			"syz_test$csum_ipv4_tcp(&(0x7f0000000000)={{0x0, {0x42, 0x43, [0x44, 0x45], 0xa, 0xb, \"aabbccdd\"}, 0x0, 0x0, 0x0}, {{0x0}, \"abcd\"}})",
+			0x542e,
+		},
+	}
+	for i, test := range tests {
+		p, err := Deserialize([]byte(test.prog))
+		if err != nil {
+			t.Fatalf("failed to deserialize prog %v: %v", test.prog, err)
+		}
+		csumMap := calcChecksumsCall(p.Calls[0], i % 32)
+		for oldField, newField := range csumMap {
+			if typ, ok := newField.Type.(*sys.CsumType); ok {
+				if typ.Kind == sys.CsumTCP {
+					csum := newField.Value(i % 32)
+					if csum != uintptr(test.csum) {
+						t.Fatalf("failed to calc tcp checksum, got %x, want %x, prog: '%v'", csum, test.csum, test.prog)
+					}
+				}
+			} else {
+				t.Fatalf("non csum key %+v in csum map %+v", oldField, csumMap)
+			}
+		}
+	}
+}
+
 func TestChecksumCalcRandom(t *testing.T) {
 	rs, iters := initTest(t)
 	for i := 0; i < iters; i++ {
diff --git a/sys/decl.go b/sys/decl.go
index 57d78857..ba180683 100644
--- a/sys/decl.go
+++ b/sys/decl.go
@@ -194,6 +194,7 @@ type CsumKind int
 
 const (
 	CsumIPv4 CsumKind = iota
+	CsumTCP
 )
 
 type CsumType struct {
diff --git a/sys/socket.txt b/sys/socket.txt
index c123a5db..9e86c4de 100644
--- a/sys/socket.txt
+++ b/sys/socket.txt
@@ -138,6 +138,7 @@ sockaddr_in {
 	family	const[AF_INET, int16]
 	port	proc[int16be, 20000, 4]
 	addr	in_addr
+	pad     array[const[0, int8], 8]
 }
 
 sockaddr_storage_in {
@@ -193,6 +194,28 @@ cmsghdr {
 
 
 
+# AF_INET: TCP support
+
+resource sock_tcp[sock]
+
+socket$tcp(domain const[AF_INET], type const[SOCK_STREAM], proto const[0]) sock_tcp
+socketpair$tcp(domain const[AF_INET], type const[SOCK_STREAM], proto const[0], fds ptr[out, tcp_pair])
+accept$tcp(fd sock_tcp, peer ptr[out, sockaddr_in, opt], peerlen ptr[inout, len[peer, int32]]) sock_tcp
+accept4$tcp(fd sock_tcp, peer ptr[out, sockaddr_in, opt], peerlen ptr[inout, len[peer, int32]], flags flags[accept_flags]) sock_tcp
+bind$tcp(fd sock_tcp, addr ptr[in, sockaddr_in], addrlen len[addr])
+connect$tcp(fd sock_tcp, addr ptr[in, sockaddr_in], addrlen len[addr])
+sendto$tcp(fd sock_tcp, buf buffer[in], len len[buf], f flags[send_flags], addr ptr[in, sockaddr_in, opt], addrlen len[addr])
+recvfrom$tcp(fd sock_tcp, buf buffer[out], len len[buf], f flags[recv_flags], addr ptr[in, sockaddr_in, opt], addrlen len[addr])
+getsockname$tcp(fd sock_tcp, addr ptr[out, sockaddr_in], addrlen ptr[inout, len[addr, int32]])
+getpeername$tcp(fd sock_tcp, peer ptr[out, sockaddr_in], peerlen ptr[inout, len[peer, int32]])
+
+tcp_pair {
+	f0	sock_tcp
+	f1	sock_tcp
+}
+
+
+
 # AF_UNIX support.
 
 resource sock_unix[sock]
diff --git a/sys/sys.txt b/sys/sys.txt
index be43f078..b4e6bdf5 100644
--- a/sys/sys.txt
+++ b/sys/sys.txt
@@ -941,7 +941,7 @@ in_addr [
 	loopback	const[0x7f000001, int32be]
 # 255.255.255.255
 	broadcast	const[0xffffffff, int32be]
-}
+]
 
 in6_addr_empty {
 	a0		const[0, int64be]
diff --git a/sys/test.txt b/sys/test.txt
index 75b8428f..932ddac0 100644
--- a/sys/test.txt
+++ b/sys/test.txt
@@ -393,7 +393,8 @@ syz_test$bf1(a0 ptr[in, syz_bf_struct1])
 # Checksums
 
 syz_test$csum_encode(a0 ptr[in, syz_csum_encode])
-syz_test$csum_ipv4(a0 ptr[in, syz_csum_ipv4])
+syz_test$csum_ipv4(a0 ptr[in, syz_csum_ipv4_header])
+syz_test$csum_ipv4_tcp(a0 ptr[in, syz_csum_ipv4_tcp_packet])
 
 syz_csum_encode {
 	f0	int16
@@ -404,7 +405,24 @@ syz_csum_encode {
 	f5	array[int8, 4]
 } [packed]
 
-syz_csum_ipv4 {
-	f0	csum[ipv4, int16]
-	f1	syz_csum_encode
+syz_csum_ipv4_header {
+	csum		csum[ipv4, int16]
+	data		syz_csum_encode
+	protocol	int8
+	src_ip		int32be
+	dst_ip		int32be
+} [packed]
+
+syz_csum_tcp_header {
+	csum		csum[tcp, int16]
+} [packed]
+
+syz_csum_tcp_packet {
+	header		syz_csum_tcp_header
+	payload		array[int8]
+} [packed]
+
+syz_csum_ipv4_tcp_packet {
+	header		syz_csum_ipv4_header
+	payload		syz_csum_tcp_packet
 } [packed]
diff --git a/sys/vnet.txt b/sys/vnet.txt
index 296d0479..5e9becc7 100644
--- a/sys/vnet.txt
+++ b/sys/vnet.txt
@@ -257,6 +257,139 @@ ipv4_packet {
 	payload		ip_payload
 } [packed]
 
+################################################################################
+###################################### IP ######################################
+################################################################################
+
 ip_payload {
-	dummy		array[int8, 0:128]
+	tcp		tcp_packet
+} [packed]
+
+################################################################################
+###################################### TCP #####################################
+################################################################################
+
+# https://en.wikipedia.org/wiki/Transmission_Control_Protocol#TCP_segment_structure
+# http://www.iana.org/assignments/tcp-parameters/tcp-parameters.xhtml
+
+include <net/tcp.h>
+include <uapi/linux/tcp.h>
+
+tcp_option [
+	generic		tcp_generic_option
+	nop		tcp_nop_option
+	eol		tcp_eol_option
+	mss		tcp_mss_option
+	window		tcp_window_option
+	sack_perm	tcp_sack_perm_option
+	sack		tcp_sack_option
+	timestamp	tcp_timestamp_option
+	md5sig		tcp_md5sig_option
+	fastopen	tcp_fastopen_option
+# TODO: TCPOPT_EXP option
+] [varlen]
+
+tcp_option_types = TCPOPT_NOP, TCPOPT_EOL, TCPOPT_MSS, TCPOPT_WINDOW, TCPOPT_SACK_PERM, TCPOPT_SACK, TCPOPT_TIMESTAMP, TCPOPT_MD5SIG, TCPOPT_FASTOPEN, TCPOPT_EXP
+
+tcp_generic_option {
+	type		flags[tcp_option_types, int8]
+	length		len[parent, int8]
+	data		array[int8, 0:16]
+} [packed]
+
+# https://tools.ietf.org/html/rfc793#section-3.1
+tcp_nop_option {
+	type		const[TCPOPT_NOP, int8]
+} [packed]
+
+# https://tools.ietf.org/html/rfc793#section-3.1
+tcp_eol_option {
+	type		const[TCPOPT_EOL, int8]
+} [packed]
+
+# https://tools.ietf.org/html/rfc793#section-3.1
+tcp_mss_option {
+	type		const[TCPOPT_MSS, int8]
+	length		len[parent, int8]
+	seg_size	int16
+} [packed]
+
+# https://tools.ietf.org/html/rfc7323#section-2
+tcp_window_option {
+	type		const[TCPOPT_WINDOW, int8]
+	length		len[parent, int8]
+	shift		int8
+} [packed]
+
+# https://tools.ietf.org/html/rfc2018#section-2
+tcp_sack_perm_option {
+	type		const[TCPOPT_SACK_PERM, int8]
+	length		len[parent, int8]
+} [packed]
+
+# https://tools.ietf.org/html/rfc2018#section-3
+tcp_sack_option {
+	type		const[TCPOPT_SACK, int8]
+	length		len[parent, int8]
+	data		array[int32be]
+} [packed]
+
+# https://tools.ietf.org/html/rfc7323#section-3
+tcp_timestamp_option {
+	type		const[TCPOPT_TIMESTAMP, int8]
+	length		len[parent, int8]
+	tsval		int32be
+	tsecr		int32be
+} [packed]
+
+# https://tools.ietf.org/html/rfc2385#section-3.0
+tcp_md5sig_option {
+	type		const[TCPOPT_MD5SIG, int8]
+	length		len[parent, int8]
+	md5		array[int8, 16]
+} [packed]
+
+# https://tools.ietf.org/html/rfc7413#section-4.1.1
+tcp_fastopen_option {
+	type		const[TCPOPT_FASTOPEN, int8]
+	length		len[parent, int8]
+	data		array[int8, 0:16]
+} [packed]
+
+tcp_options {
+	options		array[tcp_option]
+} [packed, align_4]
+
+# TODO: extract sequence numbers from packets
+tcp_seq_num [
+	init	const[0x56565656, int32be]
+	next	const[0x56565657, int32be]
+	nextn	int32be[0x56565656:0x56566000]
+	random	int32be
+]
+
+tcp_flags = 0, TCPHDR_FIN, TCPHDR_SYN, TCPHDR_RST, TCPHDR_PSH, TCPHDR_ACK, TCPHDR_URG, TCPHDR_ECE, TCPHDR_CWR, TCPHDR_SYN_ECN
+
+tcp_header {
+	src_port	proc[int16be, 20000, 4]
+	dst_port	proc[int16be, 20000, 4]
+	seq_num		tcp_seq_num
+	ack_num		tcp_seq_num
+	ns		int8:1
+	reserved	const[0, int8:3]
+	data_off	bytesize4[parent, int8:4]
+	flags		flags[tcp_flags, int8]
+	window_size	int16be
+	csum		csum[tcp, int16be]
+	urg_ptr		int16be
+	options		tcp_options
+} [packed]
+
+tcp_packet {
+	header		tcp_header
+	payload		tcp_payload
+} [packed]
+
+tcp_payload {
+	payload		array[int8]
 } [packed]
diff --git a/sys/vnet_amd64.const b/sys/vnet_amd64.const
index cce212a4..9d9a8855 100644
--- a/sys/vnet_amd64.const
+++ b/sys/vnet_amd64.const
@@ -101,3 +101,22 @@ IPPROTO_TCP = 6
 IPPROTO_TP = 29
 IPPROTO_UDP = 17
 IPPROTO_UDPLITE = 136
+TCPHDR_ACK = 16
+TCPHDR_CWR = 128
+TCPHDR_ECE = 64
+TCPHDR_FIN = 1
+TCPHDR_PSH = 8
+TCPHDR_RST = 4
+TCPHDR_SYN = 2
+TCPHDR_SYN_ECN = 194
+TCPHDR_URG = 32
+TCPOPT_EOL = 0
+TCPOPT_EXP = 254
+TCPOPT_FASTOPEN = 34
+TCPOPT_MD5SIG = 19
+TCPOPT_MSS = 2
+TCPOPT_NOP = 1
+TCPOPT_SACK = 5
+TCPOPT_SACK_PERM = 4
+TCPOPT_TIMESTAMP = 8
+TCPOPT_WINDOW = 3
diff --git a/sys/vnet_arm64.const b/sys/vnet_arm64.const
index cce212a4..9d9a8855 100644
--- a/sys/vnet_arm64.const
+++ b/sys/vnet_arm64.const
@@ -101,3 +101,22 @@ IPPROTO_TCP = 6
 IPPROTO_TP = 29
 IPPROTO_UDP = 17
 IPPROTO_UDPLITE = 136
+TCPHDR_ACK = 16
+TCPHDR_CWR = 128
+TCPHDR_ECE = 64
+TCPHDR_FIN = 1
+TCPHDR_PSH = 8
+TCPHDR_RST = 4
+TCPHDR_SYN = 2
+TCPHDR_SYN_ECN = 194
+TCPHDR_URG = 32
+TCPOPT_EOL = 0
+TCPOPT_EXP = 254
+TCPOPT_FASTOPEN = 34
+TCPOPT_MD5SIG = 19
+TCPOPT_MSS = 2
+TCPOPT_NOP = 1
+TCPOPT_SACK = 5
+TCPOPT_SACK_PERM = 4
+TCPOPT_TIMESTAMP = 8
+TCPOPT_WINDOW = 3
diff --git a/sys/vnet_ppc64le.const b/sys/vnet_ppc64le.const
index cce212a4..9d9a8855 100644
--- a/sys/vnet_ppc64le.const
+++ b/sys/vnet_ppc64le.const
@@ -101,3 +101,22 @@ IPPROTO_TCP = 6
 IPPROTO_TP = 29
 IPPROTO_UDP = 17
 IPPROTO_UDPLITE = 136
+TCPHDR_ACK = 16
+TCPHDR_CWR = 128
+TCPHDR_ECE = 64
+TCPHDR_FIN = 1
+TCPHDR_PSH = 8
+TCPHDR_RST = 4
+TCPHDR_SYN = 2
+TCPHDR_SYN_ECN = 194
+TCPHDR_URG = 32
+TCPOPT_EOL = 0
+TCPOPT_EXP = 254
+TCPOPT_FASTOPEN = 34
+TCPOPT_MD5SIG = 19
+TCPOPT_MSS = 2
+TCPOPT_NOP = 1
+TCPOPT_SACK = 5
+TCPOPT_SACK_PERM = 4
+TCPOPT_TIMESTAMP = 8
+TCPOPT_WINDOW = 3
diff --git a/sysgen/sysgen.go b/sysgen/sysgen.go
index 832f5d4b..3da19247 100644
--- a/sysgen/sysgen.go
+++ b/sysgen/sysgen.go
@@ -509,6 +509,8 @@ func generateArg(
 		switch a[0] {
 		case "ipv4":
 			kind = "CsumIPv4"
+		case "tcp":
+			kind = "CsumTCP"
 		default:
 			failf("unknown checksum kind '%v'", a[0])
 		}