diff --git a/addon/bill_invoices.go b/addon/bill_invoices.go
index 347ccc0..64d09a3 100644
--- a/addon/bill_invoices.go
+++ b/addon/bill_invoices.go
@@ -1,8 +1,6 @@
 package finvoice
 
 import (
-	"strings"
-
 	"github.com/invopop/gobl/bill"
 	"github.com/invopop/gobl/cbc"
 	"github.com/invopop/gobl/pay"
@@ -76,14 +74,14 @@ func firstCreditTransferHasIBAN(val any) bool {
 	return cts[0] != nil && cts[0].IBAN != ""
 }
 
-// normalizePayInstructions strips the grouping spaces conventionally used
-// when displaying Finnish reference numbers and RF references.
+// normalizePayInstructions drops the grouping spaces conventionally used when
+// displaying Finnish reference numbers and RF references.
 func normalizePayInstructions(instr *pay.Instructions) {
-	instr.Ref = cbc.Code(strings.ReplaceAll(instr.Ref.String(), " ", ""))
+	instr.Ref = cbc.NormalizeAlphanumericalCode(instr.Ref)
 }
 
 // normalizePayCreditTransfer converts the IBAN to its machine form: no
 // grouping spaces, upper case.
 func normalizePayCreditTransfer(ct *pay.CreditTransfer) {
-	ct.IBAN = strings.ToUpper(strings.ReplaceAll(ct.IBAN, " ", ""))
+	ct.IBAN = cbc.NormalizeAlphanumericalCode(ct.IBAN)
 }
diff --git a/addon/bill_invoices_test.go b/addon/bill_invoices_test.go
index 4f8e69a..d7b7659 100644
--- a/addon/bill_invoices_test.go
+++ b/addon/bill_invoices_test.go
@@ -287,7 +287,7 @@ func TestNormalization(t *testing.T) {
 		inv := testInvoiceStandard(t)
 		inv.Payment.Instructions.CreditTransfer[0].IBAN = "fi21 1234 5600 0007 85"
 		require.NoError(t, inv.Calculate())
-		assert.Equal(t, "FI2112345600000785", inv.Payment.Instructions.CreditTransfer[0].IBAN)
+		assert.Equal(t, "FI2112345600000785", inv.Payment.Instructions.CreditTransfer[0].IBAN.String())
 		assert.NoError(t, rules.Validate(inv))
 	})
 
diff --git a/go.mod b/go.mod
index 50c6155..f965e6a 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module github.com/invopop/gobl.fi.finvoice
 go 1.25.0
 
 require (
-	github.com/invopop/gobl v0.503.1-0.20260803162610-15cd103fc60a
+	github.com/invopop/gobl v0.504.0
 	github.com/stretchr/testify v1.11.1
 )
 
diff --git a/go.sum b/go.sum
index b896af8..6b66a22 100644
--- a/go.sum
+++ b/go.sum
@@ -21,8 +21,8 @@ github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
-github.com/invopop/gobl v0.503.1-0.20260803162610-15cd103fc60a h1:cs0QnFnU+JTB5FFLhGJlsELFbyPRsbRnwOkA/PcuxL4=
-github.com/invopop/gobl v0.503.1-0.20260803162610-15cd103fc60a/go.mod h1:HmiEdQreTSQYyNbhs81VKTmI7BAJKYC/6enh9RDwnE0=
+github.com/invopop/gobl v0.504.0 h1:RLmZmeAk9RL4rkMUc7xQfC70/RGiBeekRwVgMsMthQA=
+github.com/invopop/gobl v0.504.0/go.mod h1:HmiEdQreTSQYyNbhs81VKTmI7BAJKYC/6enh9RDwnE0=
 github.com/invopop/jsonschema v0.14.0 h1:MHQqLhvpNUZfw+hM3AZDYK7jxO8FZoQeQM77g8iyZjg=
 github.com/invopop/jsonschema v0.14.0/go.mod h1:ygm6C2EaVNMBDPpaPlnOA2pFAxBnxGjFlMZABxm9n2I=
 github.com/invopop/yaml v0.3.1 h1:f0+ZpmhfBSS4MhG+4HYseMdJhoeeopbSKbq5Rpeelso=