diff --git a/htdocs/core/lib/functions.lib.php b/htdocs/core/lib/functions.lib.php
index 26293ecc5f5..8250671598f 100644
--- a/htdocs/core/lib/functions.lib.php
+++ b/htdocs/core/lib/functions.lib.php
@@ -7467,7 +7467,7 @@ function get_exdir($num, $level, $alpha, $withoutslash, $object, $modulepart = '
 		// In a future, we may distribute directories on several levels depending on setup and object.
 		// Here, $object->id, $object->ref and $modulepart are required.
 		//var_dump($modulepart);
-		$path = dol_sanitizeFileName(empty($object->ref) ? (string) (property_exists($object, 'id') ? $object->id : '') : $object->ref);
+		$path = dol_sanitizeFileName(empty($object->ref) ? (string) ((is_object($object) && property_exists($object, 'id')) ? $object->id : '') : $object->ref);
 	}
 
 	if (empty($withoutslash) && !empty($path)) {