diff --git a/modules/customer-invoices/src/web/proformas/update/ui/editors/proforma-update-header-editor.tsx b/modules/customer-invoices/src/web/proformas/update/ui/editors/proforma-update-header-editor.tsx
index 6b0c9459..262a2d39 100644
--- a/modules/customer-invoices/src/web/proformas/update/ui/editors/proforma-update-header-editor.tsx
+++ b/modules/customer-invoices/src/web/proformas/update/ui/editors/proforma-update-header-editor.tsx
@@ -68,6 +68,7 @@ export const ProformaUpdateHeaderEditor = ({
           name="series"
           placeholder={t("form_fields.proformas.series.placeholder")}
           readOnly={readOnly}
+          required
         />
 
         <DatePickerField