diff --git a/src/Bo/BoBankAccount.php b/src/Bo/BoBankAccount.php
index fa69055..30cc042 100644
--- a/src/Bo/BoBankAccount.php
+++ b/src/Bo/BoBankAccount.php
@@ -25,7 +25,7 @@ public function getAccountTile(): string
 
     public function isValid(): bool
     {
-        if (preg_match('/^\d{22}$/', $this->bank_account_number) !== 1) {
+        if (preg_match('/^([a-zA-Z]{3})\+([0-9]{22})$/', $this->bank_account_number) !== 1) {
             return false;
         }