diff --git a/CRM/RelateEntities/Settings.php b/CRM/RelateEntities/Settings.php
index e0ba180..4a040a9 100644
--- a/CRM/RelateEntities/Settings.php
+++ b/CRM/RelateEntities/Settings.php
@@ -5,7 +5,7 @@ class CRM_RelateEntities_Settings {
   public static function install() {
     CRM_Core_DAO::executeQuery("
       CREATE TABLE IF NOT EXISTS `civicrm_relate_entities` (
-        `id` int(10) UNSIGNED NOT NULL,
+        `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT,
         `entity_table_a` varchar(255) NOT NULL,
         `entity_table_b` varchar(255) NOT NULL,
         `entity_id_a` int(10) UNSIGNED NOT NULL,