diff --git a/src/Cron/CronExpression.php b/src/Cron/CronExpression.php
index d045361f..6b49514d 100644
--- a/src/Cron/CronExpression.php
+++ b/src/Cron/CronExpression.php
@@ -76,7 +76,7 @@ public static function factory($expression, FieldFactory $fieldFactory = null)
             $expression = $mappings[$expression];
         }
 
-        return new self($expression, $fieldFactory ?: new FieldFactory());
+        return new static($expression, $fieldFactory ?: new FieldFactory());
     }
 
     /**