diff --git a/expr/ct.go b/expr/ct.go
index 515cebc..5808463 100644
--- a/expr/ct.go
+++ b/expr/ct.go
@@ -22,23 +22,71 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+// CtKey specifies which piece of conntrack information should be loaded. See
+// also https://wiki.nftables.org/wiki-nftables/index.php/Matching_connection_tracking_stateful_metainformation
+type CtKey uint32
+
+// Possible CtKey values.
+const (
+	CtKeySTATE      CtKey = unix.NFT_CT_STATE
+	CtKeyDIRECTION  CtKey = unix.NFT_CT_DIRECTION
+	CtKeySTATUS     CtKey = unix.NFT_CT_STATUS
+	CtKeyMARK       CtKey = unix.NFT_CT_MARK
+	CtKeySECMARK    CtKey = unix.NFT_CT_SECMARK
+	CtKeyEXPIRATION CtKey = unix.NFT_CT_EXPIRATION
+	CtKeyHELPER     CtKey = unix.NFT_CT_HELPER
+	CtKeyL3PROTOCOL CtKey = unix.NFT_CT_L3PROTOCOL
+	CtKeySRC        CtKey = unix.NFT_CT_SRC
+	CtKeyDST        CtKey = unix.NFT_CT_DST
+	CtKeyPROTOCOL   CtKey = unix.NFT_CT_PROTOCOL
+	CtKeyPROTOSRC   CtKey = unix.NFT_CT_PROTO_SRC
+	CtKeyPROTODST   CtKey = unix.NFT_CT_PROTO_DST
+	CtKeyLABELS     CtKey = unix.NFT_CT_LABELS
+	CtKeyPKTS       CtKey = unix.NFT_CT_PKTS
+	CtKeyBYTES      CtKey = unix.NFT_CT_BYTES
+	CtKeyAVGPKT     CtKey = unix.NFT_CT_AVGPKT
+	CtKeyZONE       CtKey = unix.NFT_CT_ZONE
+	CtKeyEVENTMASK  CtKey = unix.NFT_CT_EVENTMASK
+)
+
 // Ct defines type for NFT connection tracking
 type Ct struct {
-	Register uint32
-	Key      uint32
+	Register       uint32
+	SourceRegister bool
+	Key            CtKey
 }
 
 func (e *Ct) marshal() ([]byte, error) {
-	data, err := netlink.MarshalAttributes([]netlink.Attribute{
-		{Type: unix.NFTA_CT_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
-		{Type: unix.NFTA_CT_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
-	})
+	regData := []byte{}
+	exprData, err := netlink.MarshalAttributes(
+		[]netlink.Attribute{
+			{Type: unix.NFTA_CT_KEY, Data: binaryutil.BigEndian.PutUint32(uint32(e.Key))},
+		},
+	)
 	if err != nil {
 		return nil, err
 	}
+	if e.SourceRegister {
+		regData, err = netlink.MarshalAttributes(
+			[]netlink.Attribute{
+				{Type: unix.NFTA_CT_SREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
+			},
+		)
+	} else {
+		regData, err = netlink.MarshalAttributes(
+			[]netlink.Attribute{
+				{Type: unix.NFTA_CT_DREG, Data: binaryutil.BigEndian.PutUint32(e.Register)},
+			},
+		)
+	}
+	if err != nil {
+		return nil, err
+	}
+	exprData = append(exprData, regData...)
+
 	return netlink.MarshalAttributes([]netlink.Attribute{
 		{Type: unix.NFTA_EXPR_NAME, Data: []byte("ct\x00")},
-		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: data},
+		{Type: unix.NLA_F_NESTED | unix.NFTA_EXPR_DATA, Data: exprData},
 	})
 }
 
@@ -51,7 +99,7 @@ func (e *Ct) unmarshal(data []byte) error {
 	for ad.Next() {
 		switch ad.Type() {
 		case unix.NFTA_CT_KEY:
-			e.Key = ad.Uint32()
+			e.Key = CtKey(ad.Uint32())
 		case unix.NFTA_CT_DREG:
 			e.Register = ad.Uint32()
 		}
diff --git a/nftables_test.go b/nftables_test.go
index 9d846db..3283fbf 100644
--- a/nftables_test.go
+++ b/nftables_test.go
@@ -772,6 +772,65 @@ func TestCt(t *testing.T) {
 	}
 }
 
+func TestCtSet(t *testing.T) {
+	want := [][]byte{
+		// batch begin
+		[]byte("\x00\x00\x00\x0a"),
+		// sudo nft add rule filter forward ct mark set 1
+		[]byte("\x02\x00\x00\x00\x0b\x00\x01\x00\x66\x69\x6c\x74\x65\x72\x00\x00\x0c\x00\x02\x00\x66\x6f\x72\x77\x61\x72\x64\x00\x50\x00\x04\x80\x2c\x00\x01\x80\x0e\x00\x01\x00\x69\x6d\x6d\x65\x64\x69\x61\x74\x65\x00\x00\x00\x18\x00\x02\x80\x08\x00\x01\x00\x00\x00\x00\x01\x0c\x00\x02\x80\x08\x00\x01\x00\x01\x00\x00\x00\x20\x00\x01\x80\x07\x00\x01\x00\x63\x74\x00\x00\x14\x00\x02\x80\x08\x00\x02\x00\x00\x00\x00\x03\x08\x00\x04\x00\x00\x00\x00\x01"),
+		// batch end
+		[]byte("\x00\x00\x00\x0a"),
+	}
+
+	c := &nftables.Conn{
+		TestDial: func(req []netlink.Message) ([]netlink.Message, error) {
+			for idx, msg := range req {
+				b, err := msg.MarshalBinary()
+				if err != nil {
+					t.Fatal(err)
+				}
+				if len(b) < 16 {
+					continue
+				}
+				b = b[16:]
+				if len(want) == 0 {
+					t.Errorf("no want entry for message %d: %x", idx, b)
+					continue
+				}
+				if got, want := b, want[0]; !bytes.Equal(got, want) {
+					t.Errorf("message %d: %s", idx, linediff(nfdump(got), nfdump(want)))
+				}
+				want = want[1:]
+			}
+			return req, nil
+		},
+	}
+
+	c.AddRule(&nftables.Rule{
+		Table: &nftables.Table{Name: "filter", Family: nftables.TableFamilyIPv4},
+		Chain: &nftables.Chain{
+			Name: "forward",
+		},
+		Exprs: []expr.Any{
+			//	[ immediate reg 1 0x00000001 ]
+			&expr.Immediate{
+				Register: 1,
+				Data:     binaryutil.NativeEndian.PutUint32(1),
+			},
+			// [ ct set mark with reg 1 ]
+			&expr.Ct{
+				Key:            expr.CtKeyMARK,
+				Register:       1,
+				SourceRegister: true,
+			},
+		},
+	})
+
+	if err := c.Flush(); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestAddRuleWithPosition(t *testing.T) {
 	want := [][]byte{
 		// batch begin