diff --git a/includes/form.inc b/includes/form.inc
index faaa75d5f520772980b0b174a33c93002207b6ec..ed5fa28505c441920c61b595d8d2ba11521f4951 100644
--- a/includes/form.inc
+++ b/includes/form.inc
@@ -2977,12 +2977,13 @@ function theme_tableselect($variables) {
     // Add an empty header or a "Select all" checkbox to provide room for the
     // checkboxes/radios in the first table column.
     if ($element['#js_select']) {
-      // Add a "Select all" checkbox when checkboxes are displayed.
+      // Add a "Select all" checkbox.
       drupal_add_js('misc/tableselect.js');
       array_unshift($header, array('class' => array('select-all')));
     }
     else {
-      // Add an empty header when radio buttons are displayed.
+      // Add an empty header when radio buttons are displayed or a "Select all"
+      // checkbox is not desired.
       array_unshift($header, '');
     }
   }