diff --git a/session_api.module b/session_api.module
index 2d3782f..a7e0f7a 100644
--- a/session_api.module
+++ b/session_api.module
@@ -110,7 +110,7 @@ function session_api_menu() {
 function session_api_cron() {
   // Fetch list of outdated sids.
   $query = db_select('session_api', 'sap');
-  $query->leftJoin('sessions', 's', 'sap.sid = s.sid');
+  $query->leftJoin('sessions', 's', 'sap.session_id = s.sid');
   $query->fields('sap', array('sid'));
   $query->condition('sap.timestamp', REQUEST_TIME - variable_get('session_api_cookie_expire_time', 2592000), '<');
   $outdated_sids = $query->execute()->fetchCol();