diff --git a/modules/system/system.admin.inc b/modules/system/system.admin.inc
index b08f418..4d4a1c2 100644
--- a/modules/system/system.admin.inc
+++ b/modules/system/system.admin.inc
@@ -280,6 +280,10 @@ function system_themes_admin_form_submit($form, &$form_state) {
   drupal_set_message(t('The configuration options have been saved.'));
   variable_set('admin_theme', $form_state['values']['admin_theme']);
   variable_set('node_admin_theme', $form_state['values']['node_admin_theme']);
+
+    // Initialize the theme's blocks, if not already initialized,
+    // so the essential blocks appear.
+    block_theme_initialize($form_state['values']['admin_theme']);
 }
 
 /**