diff --git a/config/verifactu.php b/config/verifactu.php
index fdd8d6c..40bca23 100644
--- a/config/verifactu.php
+++ b/config/verifactu.php
@@ -2,6 +2,7 @@
 
 return [
     'enabled' => true,
+    'system_id' => env('VERIFACTU_SYSTEM_ID', '01'),
     'default_currency' => 'EUR',
     'issuer' => [
         'name' => env('VERIFACTU_ISSUER_NAME', ''),
diff --git a/src/Services/AeatClient.php b/src/Services/AeatClient.php
index d1b9703..5d9c684 100644
--- a/src/Services/AeatClient.php
+++ b/src/Services/AeatClient.php
@@ -259,7 +259,7 @@ private function buildRegistration(
                 'NombreRazon' => $issuerName,
                 'NIF' => $issuerVat,
                 'NombreSistemaInformatico' => env('APP_NAME', 'LaravelVerifactu'),
-                'IdSistemaInformatico' => '01',
+                'IdSistemaInformatico' => config('verifactu.system_id', '01'),
                 'Version' => '1.0',
                 'NumeroInstalacion' => '001',
                 'TipoUsoPosibleSoloVerifactu' => 'S',