diff --git a/src/DCCDocument.ts b/src/DCCDocument.ts
index 74d8aa8ffc2873c32d452a913ae885991a967a24..23fddd168aa0fbdb29629d5d49cc5f4b464749ff 100644
--- a/src/DCCDocument.ts
+++ b/src/DCCDocument.ts
@@ -1,6 +1,7 @@
 import { Element, js2xml, xml2js } from "xml-js";
 
 import { DigitalCalibrationCertificateType, DCC } from "./DCC";
+import { DSI } from "./DSI";
 
 export class DCCDocument {
   _declaration: unknown;
@@ -15,6 +16,10 @@ export class DCCDocument {
     return new DCCDocument({
       digitalCalibrationCertificate: new DigitalCalibrationCertificateType({
         _attr: {
+          "xmlns:xsi": "http://www.w3.org/2001/XMLSchema-instance",
+          "xsi:schemaLocation": `${DCC.namespaceUrl} ${DCC.schemaLocation}`,
+          "xmlns:dcc": DCC.namespaceUrl,
+          "xmlns:si": DSI.namespaceUrl,
           schemaVersion: DCC.schemaVersion,
         },
       }),