diff --git a/lnwire/lnwire.go b/lnwire/lnwire.go
index a44c1fbb..752355e8 100644
--- a/lnwire/lnwire.go
+++ b/lnwire/lnwire.go
@@ -72,12 +72,6 @@ func writeElement(w io.Writer, element interface{}) error {
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
-	case FailCode:
-		var b [2]byte
-		binary.BigEndian.PutUint16(b[:], uint16(e))
-		if _, err := w.Write(b[:]); err != nil {
-			return err
-		}
 	case ErrorCode:
 		var b [2]byte
 		binary.BigEndian.PutUint16(b[:], uint16(e))
@@ -170,6 +164,16 @@ func writeElement(w io.Writer, element interface{}) error {
 		if _, err := w.Write(b[:]); err != nil {
 			return err
 		}
+	case OpaqueReason:
+		var l [2]byte
+		binary.BigEndian.PutUint16(l[:], uint16(len(e)))
+		if _, err := w.Write(l[:]); err != nil {
+			return err
+		}
+
+		if _, err := w.Write(e[:]); err != nil {
+			return err
+		}
 	case []byte:
 		if _, err := w.Write(e[:]); err != nil {
 			return err
@@ -339,12 +343,6 @@ func readElement(r io.Reader, element interface{}) error {
 			return err
 		}
 		*e = b[0]
-	case *FailCode:
-		var b [2]byte
-		if _, err := io.ReadFull(r, b[:]); err != nil {
-			return err
-		}
-		*e = FailCode(binary.BigEndian.Uint16(b[:]))
 	case *uint16:
 		var b [2]byte
 		if _, err := io.ReadFull(r, b[:]); err != nil {
@@ -458,6 +456,17 @@ func readElement(r io.Reader, element interface{}) error {
 		}
 		*e = wire.BitcoinNet(binary.BigEndian.Uint32(b[:]))
 		return nil
+	case *OpaqueReason:
+		var l [2]byte
+		if _, err := io.ReadFull(r, l[:]); err != nil {
+			return err
+		}
+		reasonLen := binary.BigEndian.Uint16(l[:])
+
+		*e = OpaqueReason(make([]byte, reasonLen))
+		if _, err := io.ReadFull(r, *e); err != nil {
+			return err
+		}
 	case []byte:
 		if _, err := io.ReadFull(r, e); err != nil {
 			return err
diff --git a/lnwire/update_fail_htlc.go b/lnwire/update_fail_htlc.go
index c1f31a89..c8d663e5 100644
--- a/lnwire/update_fail_htlc.go
+++ b/lnwire/update_fail_htlc.go
@@ -71,13 +71,18 @@ func (c FailCode) String() string {
 	}
 }
 
+// OpaqueReason is an opaque encrypted byte slice that encodes the exact
+// failure reason and additional some supplemental data. The contents of this
+// slice can only be decrypted by the sender of the original HTLC.
+type OpaqueReason []byte
+
 // UpdateFailHTLC is sent by Alice to Bob in order to remove a previously added
 // HTLC. Upon receipt of an UpdateFailHTLC the HTLC should be removed from the
 // next commitment transaction, with the UpdateFailHTLC propagated backwards in
 // the route to fully undo the HTLC.
 type UpdateFailHTLC struct {
-	// ChannelPoint is the particular active channel that this UpdateFailHTLC
-	// is binded to.
+	// ChannelPoint is the particular active channel that this
+	// UpdateFailHTLC is binded to.
 	ChannelPoint wire.OutPoint
 
 	// ID references which HTLC on the remote node's commitment transaction
@@ -88,7 +93,7 @@ type UpdateFailHTLC struct {
 	// failed. This blob is only fully decryptable by the initiator of the
 	// HTLC message.
 	// TODO(roasbeef): properly format the encrypted failure reason
-	Reason []byte
+	Reason OpaqueReason
 }
 
 // A compile time check to ensure UpdateFailHTLC implements the lnwire.Message
@@ -106,7 +111,7 @@ func (c *UpdateFailHTLC) Decode(r io.Reader, pver uint32) error {
 	err := readElements(r,
 		&c.ChannelPoint,
 		&c.ID,
-		c.Reason[:],
+		&c.Reason,
 	)
 	if err != nil {
 		return err
@@ -123,7 +128,7 @@ func (c *UpdateFailHTLC) Encode(w io.Writer, pver uint32) error {
 	err := writeElements(w,
 		c.ChannelPoint,
 		c.ID,
-		c.Reason[:],
+		c.Reason,
 	)
 	if err != nil {
 		return err
diff --git a/lnwire/update_fail_htlc_test.go b/lnwire/update_fail_htlc_test.go
index 923e4e3b..dfce45b8 100644
--- a/lnwire/update_fail_htlc_test.go
+++ b/lnwire/update_fail_htlc_test.go
@@ -12,7 +12,7 @@ func TestUpdateFailHTLC(t *testing.T) {
 		ChannelPoint: *outpoint1,
 		ID:           22,
 	}
-	copy(cancelMsg.Reason[:], bytes.Repeat([]byte{21}, 20))
+	cancelMsg.Reason = []byte{byte(UnknownDestination)}
 
 	// Next encode the UFH message into an empty bytes buffer.
 	var b bytes.Buffer