diff --git a/src/js/pdf.js b/src/js/pdf.js
index 1e28e29..911a94b 100644
--- a/src/js/pdf.js
+++ b/src/js/pdf.js
@@ -7,8 +7,9 @@
 
 const {jsPDF} = window.jspdf;
 
-var pdfPageScale = 3;
-var pdfAssumedDPI = 72;
+const certificateVersion = 1;
+const pdfPageScale = 3;
+const pdfAssumedDPI = 72;
 var pdfDoc = null;
 var pageNumber = 0;
 var pdfTitle = "";
@@ -227,6 +228,7 @@ function makeAndSaveSignedPDF(pdf, savepath, callback) {
 
     var sign = function () {
         var message = "START"
+                + "\nV:" + certificateVersion
                 + "\nHASH:" + hashstr
                 + "\nDATE:" + time()
                 + (otsbytes != "" ? "\nOTS:" + otsbytes : "")