diff --git a/src/LEOrder.php b/src/LEOrder.php
index 5ff5afe..f7a01d2 100644
--- a/src/LEOrder.php
+++ b/src/LEOrder.php
@@ -74,7 +74,7 @@ class LEOrder
      * @param string 		$notBefore 			A date string formatted like 0000-00-00T00:00:00Z (yyyy-mm-dd hh:mm:ss) at which the certificate becomes valid.
      * @param string 		$notAfter 			A date string formatted like 0000-00-00T00:00:00Z (yyyy-mm-dd hh:mm:ss) until which the certificate is valid.
      */
-    public function __construct($connector, $log, $certificateKeys, $basename, $domains, $keyType = 'rsa-4096', $notBefore, $notAfter)
+    public function __construct($connector, $log, $certificateKeys, $basename, $domains, $keyType = 'rsa-4096', $notBefore = '', $notAfter = '')
     {
         $this->connector = $connector;
         $this->basename = $basename;