diff --git a/nip47/controllers/lookup_invoice_controller.go b/nip47/controllers/lookup_invoice_controller.go
index 85f1847e..e6f862ac 100644
--- a/nip47/controllers/lookup_invoice_controller.go
+++ b/nip47/controllers/lookup_invoice_controller.go
@@ -2,11 +2,13 @@ package controllers
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"strings"
 
 	"github.com/getAlby/hub/logger"
 	"github.com/getAlby/hub/nip47/models"
+	"github.com/getAlby/hub/transactions"
 	"github.com/nbd-wtf/go-nostr"
 	decodepay "github.com/nbd-wtf/ln-decodepay"
 	"github.com/sirupsen/logrus"
@@ -72,10 +74,15 @@ func (controller *nip47Controller) HandleLookupInvoiceEvent(ctx context.Context,
 			"payment_hash":     paymentHash,
 		}).Infof("Failed to lookup invoice: %v", err)
 
+		code := models.ERROR_INTERNAL
+		if errors.Is(err, transactions.NewNotFoundError()) {
+			code = models.ERROR_NOT_FOUND
+		}
+
 		publishResponse(&models.Response{
 			ResultType: nip47Request.Method,
 			Error: &models.Error{
-				Code:    models.ERROR_INTERNAL,
+				Code:    code,
 				Message: err.Error(),
 			},
 		}, nostr.Tags{})
diff --git a/nip47/models/models.go b/nip47/models/models.go
index 34f8ef79..f89380f0 100644
--- a/nip47/models/models.go
+++ b/nip47/models/models.go
@@ -30,6 +30,7 @@ const (
 	ERROR_EXPIRED              = "EXPIRED"
 	ERROR_RESTRICTED           = "RESTRICTED"
 	ERROR_BAD_REQUEST          = "BAD_REQUEST"
+	ERROR_NOT_FOUND            = "NOT_FOUND"
 	OTHER                      = "OTHER"
 )
 
diff --git a/transactions/transactions_service.go b/transactions/transactions_service.go
index 2bbf6a30..e01af20c 100644
--- a/transactions/transactions_service.go
+++ b/transactions/transactions_service.go
@@ -32,6 +32,17 @@ type TransactionsService interface {
 
 type Transaction = db.Transaction
 
+type notFoundError struct {
+}
+
+func NewNotFoundError() error {
+	return &notFoundError{}
+}
+
+func (err *notFoundError) Error() string {
+	return "Not Found"
+}
+
 const (
 	TRANSACTION_TYPE_INCOMING = "incoming"
 	TRANSACTION_TYPE_OUTGOING = "outgoing"
@@ -290,7 +301,7 @@ func (svc *transactionsService) LookupTransaction(ctx context.Context, paymentHa
 	}
 
 	if result.RowsAffected == 0 {
-		return nil, errors.New("transaction not found")
+		return nil, NewNotFoundError()
 	}
 
 	if transaction.State == TRANSACTION_STATE_PENDING {