diff --git a/misc/tabledrag.js b/misc/tabledrag.js
index fed674c..a238072 100644
--- a/misc/tabledrag.js
+++ b/misc/tabledrag.js
@@ -125,7 +125,8 @@ Drupal.tableDrag.prototype.initColumns = function () {
       var field = $('.' + this.tableSettings[group][d].target + ':first', this.table);
       if (field.length && this.tableSettings[group][d].hidden) {
         var hidden = this.tableSettings[group][d].hidden;
-        var cell = field.closest('td');
+        // Find the parent cell -- whether the match was in a td or th element.
+        var cell = field.closest('td, th');
         break;
       }
     }
@@ -134,7 +135,16 @@ Drupal.tableDrag.prototype.initColumns = function () {
     if (hidden && cell[0]) {
       // Add 1 to our indexes. The nth-child selector is 1 based, not 0 based.
       // Match immediate children of the parent element to allow nesting.
-      var columnIndex = $('> td', cell.parent()).index(cell.get(0)) + 1;
+      // Uses tagName (TH or TD) so selector works regardless of cell type. 
+      var columnIndex = $('> '+cell[0].tagName, cell.parent()).index(cell.get(0)) + 1;
+      // Check whether the matching cell is in a row containing colspans.
+      // If so, adjust columnIndex accordingly.
+      var origIndex = columnIndex;
+      cell.parent().children().each(function (n) {
+        if (n < origIndex && this.colSpan && this.colSpan > 1) {
+          columnIndex += this.colSpan - 1;
+        }
+      });
       $('> thead > tr, > tbody > tr, > tr', this.table).each(function () {
         // Get the columnIndex and adjust for any colspans in this row.
         var index = columnIndex;