diff --git a/build.gradle.kts b/build.gradle.kts
index 8b072e7..12528ba 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -12,7 +12,7 @@ val jvmVersion = JavaVersion.VERSION_11
 
 allprojects {
   group = "org.stellar.wallet-sdk"
-  version = "1.5.0"
+  version = "1.5.1"
 }
 
 subprojects {
diff --git a/wallet-sdk/src/main/kotlin/org/stellar/walletsdk/anchor/Data.kt b/wallet-sdk/src/main/kotlin/org/stellar/walletsdk/anchor/Data.kt
index 8cb381b..8c837a3 100644
--- a/wallet-sdk/src/main/kotlin/org/stellar/walletsdk/anchor/Data.kt
+++ b/wallet-sdk/src/main/kotlin/org/stellar/walletsdk/anchor/Data.kt
@@ -41,9 +41,9 @@ data class Refunds(
 @Serializable
 data class Payment(
   @SerialName("amount") val amount: String,
-  @SerialName("fee") val fee: String,
+  @SerialName("fee") val fee: String? = null,
   @SerialName("id") val id: String,
-  @SerialName("id_type") val idType: String
+  @SerialName("id_type") val idType: String? = null
 )
 
 @Serializable