diff --git a/invoices/sql_store.go b/invoices/sql_store.go
index 09bb91170..fa92ee56d 100644
--- a/invoices/sql_store.go
+++ b/invoices/sql_store.go
@@ -10,6 +10,7 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/channeldb/models"
 	"github.com/lightningnetwork/lnd/clock"
 	"github.com/lightningnetwork/lnd/lntypes"
@@ -46,6 +47,9 @@ type SQLInvoiceQueries interface { //nolint:interfacebloat
 	GetInvoice(ctx context.Context,
 		arg sqlc.GetInvoiceParams) ([]sqlc.Invoice, error)
 
+	GetInvoiceBySetID(ctx context.Context, setID []byte) ([]sqlc.Invoice,
+		error)
+
 	GetInvoiceFeatures(ctx context.Context,
 		invoiceID int64) ([]sqlc.InvoiceFeature, error)
 
@@ -343,7 +347,22 @@ func (i *SQLStore) fetchInvoice(ctx context.Context,
 		params.SetID = ref.SetID()[:]
 	}
 
-	rows, err := db.GetInvoice(ctx, params)
+	var (
+		rows []sqlc.Invoice
+		err  error
+	)
+
+	// We need to split the query based on how we intend to look up the
+	// invoice. If only the set ID is given then we want to have an exact
+	// match on the set ID. If other fields are given, we want to match on
+	// those fields and the set ID but with a less strict join condition.
+	if params.Hash == nil && params.PaymentAddr == nil &&
+		params.SetID != nil {
+
+		rows, err = db.GetInvoiceBySetID(ctx, params.SetID)
+	} else {
+		rows, err = db.GetInvoice(ctx, params)
+	}
 	switch {
 	case len(rows) == 0:
 		return nil, ErrInvoiceNotFound
@@ -351,8 +370,8 @@ func (i *SQLStore) fetchInvoice(ctx context.Context,
 	case len(rows) > 1:
 		// In case the reference is ambiguous, meaning it matches more
 		// than	one invoice, we'll return an error.
-		return nil, fmt.Errorf("ambiguous invoice ref: %s",
-			ref.String())
+		return nil, fmt.Errorf("ambiguous invoice ref: %s: %s",
+			ref.String(), spew.Sdump(rows))
 
 	case err != nil:
 		return nil, fmt.Errorf("unable to fetch invoice: %w", err)
@@ -1308,13 +1327,24 @@ func (s *sqlInvoiceUpdater) Finalize(_ UpdateType) error {
 // invoice and is therefore atomic. The fields to update are controlled by the
 // supplied callback.
 func (i *SQLStore) UpdateInvoice(ctx context.Context, ref InvoiceRef,
-	_ *SetID, callback InvoiceUpdateCallback) (
+	setID *SetID, callback InvoiceUpdateCallback) (
 	*Invoice, error) {
 
 	var updatedInvoice *Invoice
 
 	txOpt := SQLInvoiceQueriesTxOptions{readOnly: false}
 	txErr := i.db.ExecTx(ctx, &txOpt, func(db SQLInvoiceQueries) error {
+		if setID != nil {
+			// Make sure to use the set ID if this is an AMP update.
+			var setIDBytes [32]byte
+			copy(setIDBytes[:], setID[:])
+			ref.setID = &setIDBytes
+
+			// If we're updating an AMP invoice, we'll also only
+			// need to fetch the HTLCs for the given set ID.
+			ref.refModifier = HtlcSetOnlyModifier
+		}
+
 		invoice, err := i.fetchInvoice(ctx, db, ref)
 		if err != nil {
 			return err
diff --git a/sqldb/sqlc/invoices.sql.go b/sqldb/sqlc/invoices.sql.go
index fde02391c..5849bca06 100644
--- a/sqldb/sqlc/invoices.sql.go
+++ b/sqldb/sqlc/invoices.sql.go
@@ -170,21 +170,22 @@ const getInvoice = `-- name: GetInvoice :many
 
 SELECT i.id, i.hash, i.preimage, i.settle_index, i.settled_at, i.memo, i.amount_msat, i.cltv_delta, i.expiry, i.payment_addr, i.payment_request, i.payment_request_hash, i.state, i.amount_paid_msat, i.is_amp, i.is_hodl, i.is_keysend, i.created_at
 FROM invoices i
-LEFT JOIN amp_sub_invoices a on i.id = a.invoice_id
+LEFT JOIN amp_sub_invoices a 
+ON i.id = a.invoice_id
+AND (
+    a.set_id = $1 OR $1 IS NULL
+)
 WHERE (
-    i.id = $1 OR 
-    $1 IS NULL
-) AND (
-    i.hash = $2 OR 
+    i.id = $2 OR 
     $2 IS NULL
 ) AND (
-    i.preimage = $3 OR 
+    i.hash = $3 OR 
     $3 IS NULL
 ) AND (
-    i.payment_addr = $4 OR 
+    i.preimage = $4 OR 
     $4 IS NULL
 ) AND (
-    a.set_id = $5 OR
+    i.payment_addr = $5 OR 
     $5 IS NULL
 )
 GROUP BY i.id
@@ -192,11 +193,11 @@ LIMIT 2
 `
 
 type GetInvoiceParams struct {
+	SetID       []byte
 	AddIndex    sql.NullInt64
 	Hash        []byte
 	Preimage    []byte
 	PaymentAddr []byte
-	SetID       []byte
 }
 
 // This method may return more than one invoice if filter using multiple fields
@@ -204,11 +205,11 @@ type GetInvoiceParams struct {
 // we bubble up an error in those cases.
 func (q *Queries) GetInvoice(ctx context.Context, arg GetInvoiceParams) ([]Invoice, error) {
 	rows, err := q.db.QueryContext(ctx, getInvoice,
+		arg.SetID,
 		arg.AddIndex,
 		arg.Hash,
 		arg.Preimage,
 		arg.PaymentAddr,
-		arg.SetID,
 	)
 	if err != nil {
 		return nil, err
@@ -250,6 +251,55 @@ func (q *Queries) GetInvoice(ctx context.Context, arg GetInvoiceParams) ([]Invoi
 	return items, nil
 }
 
+const getInvoiceBySetID = `-- name: GetInvoiceBySetID :many
+SELECT i.id, i.hash, i.preimage, i.settle_index, i.settled_at, i.memo, i.amount_msat, i.cltv_delta, i.expiry, i.payment_addr, i.payment_request, i.payment_request_hash, i.state, i.amount_paid_msat, i.is_amp, i.is_hodl, i.is_keysend, i.created_at
+FROM invoices i
+INNER JOIN amp_sub_invoices a 
+ON i.id = a.invoice_id AND a.set_id = $1
+`
+
+func (q *Queries) GetInvoiceBySetID(ctx context.Context, setID []byte) ([]Invoice, error) {
+	rows, err := q.db.QueryContext(ctx, getInvoiceBySetID, setID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Invoice
+	for rows.Next() {
+		var i Invoice
+		if err := rows.Scan(
+			&i.ID,
+			&i.Hash,
+			&i.Preimage,
+			&i.SettleIndex,
+			&i.SettledAt,
+			&i.Memo,
+			&i.AmountMsat,
+			&i.CltvDelta,
+			&i.Expiry,
+			&i.PaymentAddr,
+			&i.PaymentRequest,
+			&i.PaymentRequestHash,
+			&i.State,
+			&i.AmountPaidMsat,
+			&i.IsAmp,
+			&i.IsHodl,
+			&i.IsKeysend,
+			&i.CreatedAt,
+		); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const getInvoiceFeatures = `-- name: GetInvoiceFeatures :many
 SELECT feature, invoice_id
 FROM invoice_features
diff --git a/sqldb/sqlc/querier.go b/sqldb/sqlc/querier.go
index d55d8090a..04b61c700 100644
--- a/sqldb/sqlc/querier.go
+++ b/sqldb/sqlc/querier.go
@@ -21,6 +21,7 @@ type Querier interface {
 	// from different invoices. It is the caller's responsibility to ensure that
 	// we bubble up an error in those cases.
 	GetInvoice(ctx context.Context, arg GetInvoiceParams) ([]Invoice, error)
+	GetInvoiceBySetID(ctx context.Context, setID []byte) ([]Invoice, error)
 	GetInvoiceFeatures(ctx context.Context, invoiceID int64) ([]InvoiceFeature, error)
 	GetInvoiceHTLCCustomRecords(ctx context.Context, invoiceID int64) ([]GetInvoiceHTLCCustomRecordsRow, error)
 	GetInvoiceHTLCs(ctx context.Context, invoiceID int64) ([]InvoiceHtlc, error)
diff --git a/sqldb/sqlc/queries/invoices.sql b/sqldb/sqlc/queries/invoices.sql
index 07c5ca418..b03410a51 100644
--- a/sqldb/sqlc/queries/invoices.sql
+++ b/sqldb/sqlc/queries/invoices.sql
@@ -26,7 +26,11 @@ WHERE invoice_id = $1;
 -- name: GetInvoice :many
 SELECT i.*
 FROM invoices i
-LEFT JOIN amp_sub_invoices a on i.id = a.invoice_id
+LEFT JOIN amp_sub_invoices a 
+ON i.id = a.invoice_id
+AND (
+    a.set_id = sqlc.narg('set_id') OR sqlc.narg('set_id') IS NULL
+)
 WHERE (
     i.id = sqlc.narg('add_index') OR 
     sqlc.narg('add_index') IS NULL
@@ -39,13 +43,16 @@ WHERE (
 ) AND (
     i.payment_addr = sqlc.narg('payment_addr') OR 
     sqlc.narg('payment_addr') IS NULL
-) AND (
-    a.set_id = sqlc.narg('set_id') OR
-    sqlc.narg('set_id') IS NULL
 )
 GROUP BY i.id
 LIMIT 2;
 
+-- name: GetInvoiceBySetID :many
+SELECT i.*
+FROM invoices i
+INNER JOIN amp_sub_invoices a 
+ON i.id = a.invoice_id AND a.set_id = $1;
+
 -- name: FilterInvoices :many
 SELECT
     invoices.*