diff --git a/EpcQrCode/src/commonMain/kotlin/net/codinux/banking/epcqrcode/EpcQrCodeConfig.kt b/EpcQrCode/src/commonMain/kotlin/net/codinux/banking/epcqrcode/EpcQrCodeConfig.kt
index a58fab9..b08a035 100644
--- a/EpcQrCode/src/commonMain/kotlin/net/codinux/banking/epcqrcode/EpcQrCodeConfig.kt
+++ b/EpcQrCode/src/commonMain/kotlin/net/codinux/banking/epcqrcode/EpcQrCodeConfig.kt
@@ -3,19 +3,19 @@ package net.codinux.banking.epcqrcode
 
 open class EpcQrCodeConfig(
 
-    var receiverName: String = "",
+    open val receiverName: String = "",
 
-    var iban: String = "",
+    open val iban: String = "",
 
-    var bic: String? = null,
+    open val bic: String? = null,
 
     amount: String? = null,
 
-    var reference: String? = null,
+    open val reference: String? = null,
 
-    var noteToUser: String? = null,
+    open val noteToUser: String? = null,
 
-    var encoding: EpcQrCodeCharacterSet = EpcQrCodeCharacterSet.UTF_8
+    open val encoding: EpcQrCodeCharacterSet = EpcQrCodeCharacterSet.UTF_8
 
 ) {