diff --git a/core/modules/system/system.admin.inc b/core/modules/system/system.admin.inc
index aa36ba7..13c9b12 100644
--- a/core/modules/system/system.admin.inc
+++ b/core/modules/system/system.admin.inc
@@ -637,7 +637,8 @@ function theme_system_modules_details($variables) {
     $row[] = array('class' => array('checkbox'), 'data' => drupal_render($module['enable']));
 
     // Add the module label and expand/collapse functionalty.
-    $col2 = '<label id="module-' . $key . '" for="' . $module['enable']['#id'] . '" class="module-name table-filter-text-source">' . drupal_render($module['name']) . '</label>';
+    $id = drupal_html_id('module-' . $key);
+    $col2 = '<label id="' . $id . '" for="' . $module['enable']['#id'] . '" class="module-name table-filter-text-source">' . drupal_render($module['name']) . '</label>';
     $row[] = array('class' => array('module'), 'data' => $col2);
 
     // Add the description, along with any modules it requires.