diff --git a/htdocs/core/class/commonobject.class.php b/htdocs/core/class/commonobject.class.php
index bba17f50d11..659ff4d3c5a 100644
--- a/htdocs/core/class/commonobject.class.php
+++ b/htdocs/core/class/commonobject.class.php
@@ -364,6 +364,7 @@ abstract class CommonObject
 			dol_print_error(get_class()."::isExistingObject ".$error, LOG_ERR);
 			return -1;
 		}
+		if ($ref || $ref_ext) $sql.= " AND entity = ".$conf->entity;
 
 		dol_syslog(get_class()."::isExistingObject", LOG_DEBUG);
 		$resql = $db->query($sql);