diff --git a/htlcswitch/mock.go b/htlcswitch/mock.go
index 9eac221dd..b7bc9b34a 100644
--- a/htlcswitch/mock.go
+++ b/htlcswitch/mock.go
@@ -419,12 +419,16 @@ func (o *mockObfuscator) Reextract(
 	return nil
 }
 
+var fakeHmac = []byte("hmachmachmachmachmachmachmachmac")
+
 func (o *mockObfuscator) EncryptFirstHop(failure lnwire.FailureMessage) (
 	lnwire.OpaqueReason, error) {
 
 	o.failure = failure
 
 	var b bytes.Buffer
+	b.Write(fakeHmac)
+
 	if err := lnwire.EncodeFailure(&b, failure, 0); err != nil {
 		return nil, err
 	}
@@ -436,7 +440,12 @@ func (o *mockObfuscator) IntermediateEncrypt(reason lnwire.OpaqueReason) lnwire.
 }
 
 func (o *mockObfuscator) EncryptMalformedError(reason lnwire.OpaqueReason) lnwire.OpaqueReason {
-	return reason
+	var b bytes.Buffer
+	b.Write(fakeHmac)
+
+	b.Write(reason)
+
+	return b.Bytes()
 }
 
 // mockDeobfuscator mock implementation of the failure deobfuscator which
@@ -447,7 +456,13 @@ func newMockDeobfuscator() ErrorDecrypter {
 	return &mockDeobfuscator{}
 }
 
-func (o *mockDeobfuscator) DecryptError(reason lnwire.OpaqueReason) (*ForwardingError, error) {
+func (o *mockDeobfuscator) DecryptError(reason lnwire.OpaqueReason) (
+	*ForwardingError, error) {
+
+	if !bytes.Equal(reason[:32], fakeHmac) {
+		return nil, errors.New("fake decryption error")
+	}
+	reason = reason[32:]
 
 	r := bytes.NewReader(reason)
 	failure, err := lnwire.DecodeFailure(r, 0)
diff --git a/htlcswitch/switch_test.go b/htlcswitch/switch_test.go
index 461d8875a..4d666b760 100644
--- a/htlcswitch/switch_test.go
+++ b/htlcswitch/switch_test.go
@@ -1,7 +1,6 @@
 package htlcswitch
 
 import (
-	"bytes"
 	"crypto/rand"
 	"crypto/sha256"
 	"fmt"
@@ -23,7 +22,6 @@ import (
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/ticker"
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
@@ -4088,10 +4086,10 @@ func TestSwitchHoldForward(t *testing.T) {
 	expectedFailure := &lnwire.FailInvalidOnionKey{
 		OnionSHA256: shaOnionBlob,
 	}
-	var b bytes.Buffer
-	require.NoError(t, lnwire.EncodeFailure(&b, expectedFailure, 0))
 
-	assert.Equal(t, lnwire.OpaqueReason(b.Bytes()), failPacket.Reason)
+	fwdErr, err := newMockDeobfuscator().DecryptError(failPacket.Reason)
+	require.NoError(t, err)
+	require.Equal(t, expectedFailure, fwdErr.WireMessage())
 
 	assertNumCircuits(t, c.s, 0, 0)
 
@@ -5515,10 +5513,13 @@ func testSwitchAliasInterceptFail(t *testing.T, zeroConf bool) {
 		failHtlc, ok := failPacket.htlc.(*lnwire.UpdateFailHTLC)
 		require.True(t, ok)
 
-		r := bytes.NewReader(failHtlc.Reason)
-		failure, err := lnwire.DecodeFailure(r, 0)
+		fwdErr, err := newMockDeobfuscator().DecryptError(
+			failHtlc.Reason,
+		)
 		require.NoError(t, err)
 
+		failure := fwdErr.WireMessage()
+
 		failureMsg, ok := failure.(*lnwire.FailTemporaryChannelFailure)
 		require.True(t, ok)