diff --git a/core/includes/form.inc b/core/includes/form.inc
index efb59f7..499aca9 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -1599,7 +1599,9 @@ function form_process_container($element, &$form_state) {
 }
 
 /**
- * Returns HTML for a table with radio buttons or checkboxes.
+ * Prepares a 'tableselect' #type element for rendering.
+ *
+ * Adds a column of radio buttons or checkboxes for each row of a table.
  *
  * @param $variables
  *   An associative array containing:
@@ -1637,14 +1639,8 @@ function form_process_container($element, &$form_state) {
  *       '#empty' => t('No content available.'),
  *     );
  *     @endcode
- *
- * @ingroup themeable
  */
-function theme_tableselect($variables) {
-  $element = $variables['element'];
-  $table = array(
-    '#type' => 'table',
-  );
+function form_pre_render_tableselect(array $element) {
   $rows = array();
   $header = $element['#header'];
   if (!empty($element['#options'])) {
@@ -1684,7 +1680,7 @@ function theme_tableselect($variables) {
     // checkboxes/radios in the first table column.
     if ($element['#js_select']) {
       // Add a "Select all" checkbox.
-      $table['#attached']['library'][] = 'core/drupal.tableselect';
+      $element['#attached']['library'][] = 'core/drupal.tableselect';
       array_unshift($header, array('class' => array('select-all')));
     }
     else {
@@ -1693,14 +1689,11 @@ function theme_tableselect($variables) {
       array_unshift($header, '');
     }
   }
-  $table += array(
-    '#header' => $header,
-    '#rows' => $rows,
-    '#empty' => $element['#empty'],
-    '#attributes' => $element['#attributes'],
-  );
 
-  return drupal_render($table);
+  $element['#header'] = $header;
+  $element['#rows'] = $rows;
+
+  return $element;
 }
 
 /**
@@ -1792,7 +1785,6 @@ function form_process_tableselect($element) {
  *   The processed element.
  *
  * @see form_process_tableselect()
- * @see theme_tableselect()
  */
 function form_process_table($element, &$form_state) {
   if ($element['#tableselect']) {
diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index b62ad74..d9674a9 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -2677,9 +2677,6 @@ function drupal_common_theme() {
       'render element' => 'element',
       'template' => 'textarea',
     ),
-    'tableselect' => array(
-      'render element' => 'element',
-    ),
     'form_element' => array(
       'render element' => 'element',
       'template' => 'form-element',
diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 8b4455b..c928565 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -522,10 +522,11 @@ function system_element_info() {
     '#input' => TRUE,
     '#js_select' => TRUE,
     '#multiple' => TRUE,
+    '#pre_render' => array('form_pre_render_tableselect'),
     '#process' => array('form_process_tableselect'),
     '#options' => array(),
     '#empty' => '',
-    '#theme' => 'tableselect',
+    '#theme' => 'table__tableselect',
   );
 
   // Form structure.