diff --git a/modules/forum/forum.install b/modules/forum/forum.install
index 589e3a1..ab95303 100644
--- a/modules/forum/forum.install
+++ b/modules/forum/forum.install
@@ -219,6 +219,8 @@ function forum_schema() {
     ),
     'indexes' => array(
       'forum_topics' => array('nid', 'tid', 'sticky', 'last_comment_timestamp'),
+      'created' => array('created'),
+      'last_comment_timestamp' => array('last_comment_timestamp'),
     ),
     'foreign keys' => array(
       'tracked_node' => array(
@@ -440,5 +442,13 @@ function forum_update_7003() {
 }
 
 /**
+ * Add 'created' and 'last_comment_timestamp' indexes.
+ */
+function forum_update_7004() {
+  db_add_index('forum_index', 'created', array('created'));
+  db_add_index('forum_index', 'last_comment_timestamp', array('last_comment_timestamp'));
+}
+
+/**
  * @} End of "addtogroup updates-7.x-extra"
  */