diff --git a/lnwallet/channel_test.go b/lnwallet/channel_test.go
index 5bd96b79..87d90e3c 100644
--- a/lnwallet/channel_test.go
+++ b/lnwallet/channel_test.go
@@ -70,7 +70,17 @@ func (m *mockSigner) SignOutputRaw(tx *wire.MsgTx, signDesc *SignDescriptor) ([]
 	return sig[:len(sig)-1], nil
 }
 func (m *mockSigner) ComputeInputScript(tx *wire.MsgTx, signDesc *SignDescriptor) (*InputScript, error) {
-	return nil, nil
+
+	witnessScript, err := txscript.WitnessScript(tx, signDesc.SigHashes,
+		signDesc.InputIndex, signDesc.Output.Value, signDesc.Output.PkScript,
+		txscript.SigHashAll, m.key, true)
+	if err != nil {
+		return nil, err
+	}
+
+	return &InputScript{
+		Witness: witnessScript,
+	}, nil
 }
 
 type mockNotfier struct {
diff --git a/lnwallet/script_utils.go b/lnwallet/script_utils.go
index c3cf907e..0e578270 100644
--- a/lnwallet/script_utils.go
+++ b/lnwallet/script_utils.go
@@ -639,16 +639,13 @@ func CommitSpendTimeout(signer Signer, signDesc *SignDescriptor,
 	return witnessStack, nil
 }
 
-// commitSpendRevoke constructs a valid witness allowing a node to sweep the
+// CommitSpendRevoke constructs a valid witness allowing a node to sweep the
 // settled output of a malicious counter-party who broadcasts a revoked
 // commitment transaction.
-func commitSpendRevoke(commitScript []byte, outputAmt btcutil.Amount,
-	revocationPriv *btcec.PrivateKey, sweepTx *wire.MsgTx) (wire.TxWitness, error) {
+func CommitSpendRevoke(signer Signer, signDesc *SignDescriptor,
+	sweepTx *wire.MsgTx) (wire.TxWitness, error) {
 
-	hashCache := txscript.NewTxSigHashes(sweepTx)
-	sweepSig, err := txscript.RawTxInWitnessSignature(
-		sweepTx, hashCache, 0, int64(outputAmt), commitScript,
-		txscript.SigHashAll, revocationPriv)
+	sweepSig, err := signer.SignOutputRaw(sweepTx, signDesc)
 	if err != nil {
 		return nil, err
 	}
@@ -656,29 +653,26 @@ func commitSpendRevoke(commitScript []byte, outputAmt btcutil.Amount,
 	// Place a 1 as the first item in the evaluated witness stack to
 	// force script execution to the revocation clause.
 	witnessStack := wire.TxWitness(make([][]byte, 3))
-	witnessStack[0] = sweepSig
+	witnessStack[0] = append(sweepSig, byte(txscript.SigHashAll))
 	witnessStack[1] = []byte{1}
-	witnessStack[2] = commitScript
+	witnessStack[2] = signDesc.WitnessScript
 
 	return witnessStack, nil
 }
 
-// commitSpendNoDelay constructs a valid witness allowing a node to spend their
+// CommitSpendNoDelay constructs a valid witness allowing a node to spend their
 // settled no-delay output on the counter-party's commitment transaction.
-func commitSpendNoDelay(commitScript []byte, outputAmt btcutil.Amount,
-	commitPriv *btcec.PrivateKey, sweepTx *wire.MsgTx) (wire.TxWitness, error) {
+func CommitSpendNoDelay(signer Signer, signDesc *SignDescriptor,
+	sweepTx *wire.MsgTx) (wire.TxWitness, error) {
 
 	// This is just a regular p2wkh spend which looks something like:
 	//  * witness: <sig> <pubkey>
-	hashCache := txscript.NewTxSigHashes(sweepTx)
-	witness, err := txscript.WitnessScript(sweepTx, hashCache, 0,
-		int64(outputAmt), commitScript, txscript.SigHashAll,
-		commitPriv, true)
+	inputScript, err := signer.ComputeInputScript(sweepTx, signDesc)
 	if err != nil {
 		return nil, err
 	}
 
-	return wire.TxWitness(witness), nil
+	return wire.TxWitness(inputScript.Witness), nil
 }
 
 // DeriveRevocationPubkey derives the revocation public key given the
diff --git a/lnwallet/script_utils_test.go b/lnwallet/script_utils_test.go
index 8aaa7539..eda916c8 100644
--- a/lnwallet/script_utils_test.go
+++ b/lnwallet/script_utils_test.go
@@ -107,11 +107,21 @@ func TestCommitmentSpendValidation(t *testing.T) {
 	}
 
 	// Next, we'll test bob spending with the derived revocation key to
-	// simulate the scenario when alice broadcasts this commitmen
+	// simulate the scenario when alice broadcasts this commitment
 	// transaction after it's been revoked.
 	revokePrivKey := DeriveRevocationPrivKey(bobKeyPriv, revocationPreimage)
-	bobWitnessSpend, err := commitSpendRevoke(delayScript, channelBalance,
-		revokePrivKey, sweepTx)
+	bobRevokeSigner := &mockSigner{revokePrivKey}
+	signDesc = &SignDescriptor{
+		WitnessScript: delayScript,
+		SigHashes:     txscript.NewTxSigHashes(sweepTx),
+		Output: &wire.TxOut{
+			Value: int64(channelBalance),
+		},
+		HashType:   txscript.SigHashAll,
+		InputIndex: 0,
+	}
+	bobWitnessSpend, err := CommitSpendRevoke(bobRevokeSigner, signDesc,
+		sweepTx)
 	if err != nil {
 		t.Fatalf("unable to generate revocation witness: %v", err)
 	}
@@ -128,12 +138,23 @@ func TestCommitmentSpendValidation(t *testing.T) {
 
 	// Finally, we test bob sweeping his output as normal in the case that
 	// alice broadcasts this commitment transaction.
+	bobSigner := &mockSigner{bobKeyPriv}
 	bobScriptp2wkh, err := commitScriptUnencumbered(bobKeyPub)
 	if err != nil {
 		t.Fatalf("unable to create bob p2wkh script: %v", err)
 	}
-	bobRegularSpend, err := commitSpendNoDelay(bobScriptp2wkh,
-		channelBalance, bobKeyPriv, sweepTx)
+	signDesc = &SignDescriptor{
+		WitnessScript: bobScriptp2wkh,
+		SigHashes:     txscript.NewTxSigHashes(sweepTx),
+		Output: &wire.TxOut{
+			Value:    int64(channelBalance),
+			PkScript: bobScriptp2wkh,
+		},
+		HashType:   txscript.SigHashAll,
+		InputIndex: 0,
+	}
+	bobRegularSpend, err := CommitSpendNoDelay(bobSigner, signDesc,
+		sweepTx)
 	if err != nil {
 		t.Fatalf("unable to create bob regular spend: %v", err)
 	}