diff --git a/core/misc/tabledrag.js b/core/misc/tabledrag.js
index f3c6c9e..bda5c11 100644
--- a/core/misc/tabledrag.js
+++ b/core/misc/tabledrag.js
@@ -160,7 +160,8 @@
             var field = $table.find('.' + this.tableSettings[group][d].target + ':first');
             if (field.length && this.tableSettings[group][d].hidden) {
               hidden = this.tableSettings[group][d].hidden;
-              cell = field.closest('td');
+              // Find the parent cell -- whether the match was in a td or th element.
+              cell = field.closest('td, th');
               break;
             }
           }
@@ -170,7 +171,16 @@
         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.
-          columnIndex = cell.parent().find('> td').index(cell.get(0)) + 1;
+          // Uses tagName (TH or TD) so selector works regardless of cell type.
+          columnIndex = cell.parent().find('> '+cell[0].tagName).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;
+            }
+          });
           $table.find('> thead > tr, > tbody > tr, > tr').each(this.addColspanClass(columnIndex));
         }
       }