diff --git a/src/main/kotlin/id/walt/common/SerializationUtils.kt b/src/main/kotlin/id/walt/common/SerializationUtils.kt
index c38d26a6..9db0fcb5 100644
--- a/src/main/kotlin/id/walt/common/SerializationUtils.kt
+++ b/src/main/kotlin/id/walt/common/SerializationUtils.kt
@@ -7,6 +7,7 @@ import id.walt.model.VerificationMethod
 import id.walt.sdjwt.SDMap
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.jsonObject
+import java.time.Instant
 
 @Target(AnnotationTarget.FIELD)
 annotation class VCList
@@ -42,6 +43,9 @@ annotation class DidVerificationRelationships
 @Target(AnnotationTarget.FIELD)
 annotation class SDMapProperty
 
+@Target(AnnotationTarget.FIELD)
+annotation class InstantValue
+
 class VcConverter(private val singleVC: Boolean, private val singleIfOne: Boolean, private val toVcObject: Boolean) :
     Converter {
     override fun canConvert(cls: Class<*>) = singleVC && cls == VerifiableCredential::class.java || cls == List::class.java
@@ -162,6 +166,20 @@ val sdMapConverter = object : Converter {
 
 }
 
+val klaxonInstantValueConverter = object : Converter {
+    override fun canConvert(cls: Class<*>) = cls == InstantValue::class.java
+
+    override fun fromJson(jv: JsonValue): Any? = jv.longValue ?: jv.int?.toLong()?.let {
+        Instant.ofEpochSecond(it)
+    }
+
+    override fun toJson(value: Any): String {
+        return (value as Instant).epochSecond.toString()
+    }
+
+
+}
+
 fun KlaxonWithConverters() = Klaxon()
     .fieldConverter(VCList::class, VcConverter(singleVC = false, singleIfOne = false, toVcObject = false))
     .fieldConverter(VCObjectList::class, VcConverter(singleVC = false, singleIfOne = false, toVcObject = true))
@@ -174,6 +192,7 @@ fun KlaxonWithConverters() = Klaxon()
     .fieldConverter(DidVerificationRelationships::class, didVerificationRelationshipsConverter)
     .fieldConverter(SDMapProperty::class, sdMapConverter)
     .fieldConverter(KotlinxJsonObjectField::class, kotlinxJsonObjectFieldConverter)
+    .fieldConverter(InstantValue::class, klaxonInstantValueConverter)
 
 @Deprecated("Use KlaxonWithConverters()")
 val KlaxonWithConverters = KlaxonWithConverters()
diff --git a/src/main/kotlin/id/walt/signatory/Signatory.kt b/src/main/kotlin/id/walt/signatory/Signatory.kt
index 99b7b22e..d0bd6aef 100644
--- a/src/main/kotlin/id/walt/signatory/Signatory.kt
+++ b/src/main/kotlin/id/walt/signatory/Signatory.kt
@@ -1,6 +1,7 @@
 package id.walt.signatory
 
 import com.beust.klaxon.Json
+import id.walt.common.InstantValue
 import id.walt.common.SDMapProperty
 import id.walt.credentials.w3c.VerifiableCredential
 import id.walt.credentials.w3c.W3CIssuer
@@ -39,9 +40,9 @@ data class ProofConfig(
     @Json(serializeNull = false) val nonce: String? = null,
     @Json(serializeNull = false) val proofPurpose: String? = null,
     @Json(serializeNull = false) val credentialId: String? = null,
-    @Json(serializeNull = false) val issueDate: Instant? = null, // issue date from json-input or current system time if null
-    @Json(serializeNull = false) val validDate: Instant? = null, // valid date from json-input or current system time if null
-    @Json(serializeNull = false) val expirationDate: Instant? = null,
+    @Json(serializeNull = false) @InstantValue val issueDate: Instant? = null, // issue date from json-input or current system time if null
+    @Json(serializeNull = false) @InstantValue val validDate: Instant? = null, // valid date from json-input or current system time if null
+    @Json(serializeNull = false) @InstantValue val expirationDate: Instant? = null,
     @Json(serializeNull = false) val dataProviderIdentifier: String? = null, // may be used for mapping data-sets from a custom data-provider
     @Json(serializeNull = false) val ldSignatureType: LdSignatureType? = null,
     @Json(serializeNull = false) val creator: String? = issuerDid,
@@ -90,4 +91,3 @@ abstract class Signatory : WaltIdService() {
     open fun removeTemplate(templateId: String): Unit = implementation.removeTemplate(templateId)
     open fun hasTemplateId(templateId: String): Boolean = implementation.hasTemplateId(templateId)
 }
-