diff --git a/server/src/qr.ts b/server/src/qr.ts
index 6327972..e848028 100644
--- a/server/src/qr.ts
+++ b/server/src/qr.ts
@@ -31,8 +31,8 @@ export function convertBbanToIban(bankAccountNumber: string): string {
     // Zatím napevno, nemá smysl řešit nic jiného než CZ
     iban = iban.replace('C', '12').replace('Z', '35');
     const remainder = BigInt(iban) % BigInt(97);
-    const checkDigits = BigInt(98) - remainder;
-    iban = `${COUNTRY_CODE}${checkDigits.toString()}${bankCode}${prefix}${accountNumber}`;
+    const checkDigits = (BigInt(98) - remainder).toString().padStart(2, '0');
+    iban = `${COUNTRY_CODE}${checkDigits}${bankCode}${prefix}${accountNumber}`;
     if (iban.length !== 24) {
         throw Error("Neplatná délka sestaveného IBAN: " + iban.length + ", očekáváno 24");
     }