diff --git a/message.install b/message.install
index 914cf97..61e4311 100644
--- a/message.install
+++ b/message.install
@@ -238,6 +238,9 @@ function message_schema() {
       ),
     ),
     'primary key' => array('mid'),
+    'indexes' => array(
+      'timestamp' => array('timestamp'),
+    ),
   );
   return $schema;
 }
@@ -472,3 +475,12 @@ function message_update_7009() {
   $field['settings']['message_text'] = TRUE;
   field_update_field($field);
 }
+
+/**
+ * Add an index to message.timestamp.
+ */
+function message_update_7010() {
+  $ret = array();
+  $ret[] = db_add_index('message', 'timestamp', array('timestamp'));
+  return $ret;
+}