diff --git a/src/Sermepa/Tpv/Tpv.php b/src/Sermepa/Tpv/Tpv.php
index 434f23e..3eed983 100644
--- a/src/Sermepa/Tpv/Tpv.php
+++ b/src/Sermepa/Tpv/Tpv.php
@@ -176,7 +176,7 @@ public function setDateFrecuency($dateFrecuency)
     public function setOrder($order='')
     {
         $order = trim($order);
-        if (strlen($order) <= 3 || strlen($order) > 12 || !is_numeric(substr($order, 0, 4))) {
+        if (strlen($order) <= 3 || strlen($order) > 12 ) {
             throw new TpvException('Order id must be a 4 digit string at least, maximum 12 characters.');
         }
 
@@ -994,7 +994,7 @@ protected function isExpiryDate($expirydate='')
      */
     protected function isValidOrder($order='')
     {
-        return ( strlen($order) >= 4 && strlen($order) <= 12 && is_numeric(substr($order, 0, 4)) )?true:false;
+        return ( strlen($order) >= 4 && strlen($order) <= 12 )?true:false;
 
     }