diff --git a/apps/fwupdate/custom.html b/apps/fwupdate/custom.html
index 0b1387967..26cac7da2 100644
--- a/apps/fwupdate/custom.html
+++ b/apps/fwupdate/custom.html
@@ -96,7 +96,7 @@ function onInit(device) {
     if (crcs[0] == 1787004733) { // check 6 page CRC - the 7th page isn't used in 2v20
       version = "2v20";
     } else { // for other versions all 7 pages are used, check those
-      var crc = crcs[2]; 
+      var crc = crcs[1]; 
       if (crc==1339551013) { version = "2v10.219"; ok = false; }
       if (crc==1207580954) { version = "2v10.236"; ok = false; }
       if (crc==3435933210) version = "2v11.52";