diff --git a/fints4k/src/commonMain/kotlin/net/codinux/banking/fints/model/TanChallenge.kt b/fints4k/src/commonMain/kotlin/net/codinux/banking/fints/model/TanChallenge.kt
index 9e1a37a4..5e796219 100644
--- a/fints4k/src/commonMain/kotlin/net/codinux/banking/fints/model/TanChallenge.kt
+++ b/fints4k/src/commonMain/kotlin/net/codinux/banking/fints/model/TanChallenge.kt
@@ -15,7 +15,7 @@ open class TanChallenge(
     val tanMediaIdentifier: String?,
     val bank: BankData,
     val account: AccountData? = null,
-    val timestamp: Instant = Instant.nowExt()
+    val challengeCreationTimestamp: Instant = Instant.nowExt()
 ) {
 
     var enterTanResult: EnterTanResult? = null