diff --git a/index.html b/index.html
index 52a43a5..b24580d 100644
--- a/index.html
+++ b/index.html
@@ -173,9 +173,9 @@ function detectColumn(name) {
   return null;
 }
 
-function rowId(row, idx) {
+function rowId(row, idx, headers) {
   const katoCol = dataColumns.indexOf('kato');
-  if (katoCol !== -1 && row[dataColumns[katoCol]]) return String(row[dataColumns[katoCol]]).trim();
+  if (katoCol !== -1 && row[headers[katoCol]]) return String(row[headers[katoCol]]).trim();
   return 'row_' + idx;
 }
 
@@ -470,7 +470,7 @@ function handleFile(file) {
       allData = rows.map((r, idx) => {
         const obj = {};
         headers.forEach((h, i) => { obj[h] = r[i] != null ? r[i] : ''; });
-        obj._id = rowId(obj, idx);
+        obj._id = rowId(obj, idx, headers);
         return obj;
       });
       allData.columns = headers;