diff --git a/common/src/main/kotlin/de/sipgate/federmappe/common/DefaultSerializersModule.kt b/common/src/main/kotlin/de/sipgate/federmappe/common/DefaultSerializersModule.kt
index 012d404..417bf93 100644
--- a/common/src/main/kotlin/de/sipgate/federmappe/common/DefaultSerializersModule.kt
+++ b/common/src/main/kotlin/de/sipgate/federmappe/common/DefaultSerializersModule.kt
@@ -1,11 +1,11 @@
 package de.sipgate.federmappe.common
 
-import de.sipgate.federmappe.common.serializers.TimestampSerializer
+import de.sipgate.federmappe.common.serializers.TimestampToDateSerializer
 import de.sipgate.federmappe.common.serializers.UriSerializer
 import kotlinx.serialization.modules.SerializersModule
 import kotlinx.serialization.modules.contextual
 
 val DefaultSerializersModule = SerializersModule {
-    contextual(TimestampSerializer)
+    contextual(TimestampToDateSerializer)
     contextual(UriSerializer)
 }
diff --git a/common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampSerializer.kt b/common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampToDateSerializer.kt
similarity index 97%
rename from common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampSerializer.kt
rename to common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampToDateSerializer.kt
index 75209f9..af80bbd 100644
--- a/common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampSerializer.kt
+++ b/common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampToDateSerializer.kt
@@ -12,7 +12,7 @@ import kotlinx.serialization.encoding.Encoder
 import kotlinx.serialization.encoding.decodeStructure
 import kotlinx.serialization.encoding.encodeStructure
 
-object TimestampSerializer : KSerializer<Date> {
+object TimestampToDateSerializer : KSerializer<Date> {
     override val descriptor = buildClassSerialDescriptor(serialName = "FirebaseTimestamp") {
         element<Long>("seconds")
         element<Int>("nanoseconds")
diff --git a/common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampToInstantSerializer.kt b/common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampToInstantSerializer.kt
new file mode 100644
index 0000000..a5aa577
--- /dev/null
+++ b/common/src/main/kotlin/de/sipgate/federmappe/common/serializers/TimestampToInstantSerializer.kt
@@ -0,0 +1,50 @@
+package de.sipgate.federmappe.common.serializers
+
+import kotlin.properties.Delegates
+import kotlinx.datetime.Instant
+import kotlinx.serialization.ExperimentalSerializationApi
+import kotlinx.serialization.KSerializer
+import kotlinx.serialization.descriptors.buildClassSerialDescriptor
+import kotlinx.serialization.descriptors.element
+import kotlinx.serialization.encoding.CompositeDecoder
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+import kotlinx.serialization.encoding.decodeStructure
+import kotlinx.serialization.encoding.encodeStructure
+
+object TimestampToInstantSerializer : KSerializer<Instant> {
+    override val descriptor = buildClassSerialDescriptor(serialName = "FirebaseTimestamp") {
+        element<Long>("seconds")
+        element<Int>("nanoseconds")
+    }
+
+    override fun serialize(encoder: Encoder, value: Instant) = encoder.encodeStructure(descriptor) {
+        encodeLongElement(descriptor, 0, value.epochSeconds / 1000)
+        encodeIntElement(descriptor, 1, value.nanosecondsOfSecond)
+    }
+
+    @ExperimentalSerializationApi
+    override fun deserialize(decoder: Decoder): Instant {
+        return decoder.decodeStructure(descriptor = descriptor) {
+            if (decodeSequentially()) {
+                val seconds = decodeLongElement(descriptor, 0)
+                val nanoSeconds = decodeIntElement(descriptor, 1)
+                Instant.fromEpochSeconds(seconds, nanoSeconds)
+            } else {
+                var seconds by Delegates.notNull<Long>()
+                var nanoSeconds by Delegates.notNull<Int>()
+
+                while (true) {
+                    when (val index = decodeElementIndex(descriptor)) {
+                        0 -> seconds = decodeLongElement(descriptor, 0)
+                        1 -> nanoSeconds = decodeIntElement(descriptor, 1)
+                        CompositeDecoder.DECODE_DONE -> break
+                        else -> error("Unexpected index: $index")
+                    }
+                }
+
+                Instant.fromEpochSeconds(seconds, nanoSeconds)
+            }
+        }
+    }
+}
diff --git a/common/src/test/kotlin/de/sipgate/federmappe/common/serializers/TimestampSerializerTest.kt b/common/src/test/kotlin/de/sipgate/federmappe/common/serializers/TimestampToDateSerializerTest.kt
similarity index 94%
rename from common/src/test/kotlin/de/sipgate/federmappe/common/serializers/TimestampSerializerTest.kt
rename to common/src/test/kotlin/de/sipgate/federmappe/common/serializers/TimestampToDateSerializerTest.kt
index e492cbb..d6647c9 100644
--- a/common/src/test/kotlin/de/sipgate/federmappe/common/serializers/TimestampSerializerTest.kt
+++ b/common/src/test/kotlin/de/sipgate/federmappe/common/serializers/TimestampToDateSerializerTest.kt
@@ -9,7 +9,7 @@ import org.junit.jupiter.api.Assertions
 import org.junit.jupiter.api.Test
 
 
-class TimestampSerializerTest {
+class TimestampToDateSerializerTest {
     private val epochSeconds = 1707833611L * 1000
     private val nanos = 801 / 1000000
 
@@ -20,7 +20,7 @@ class TimestampSerializerTest {
     @Test
     fun testDeserialization() {
         @Serializable
-        data class TestClass(val a: @Serializable(with = TimestampSerializer::class) Date)
+        data class TestClass(val a: @Serializable(with = TimestampToDateSerializer::class) Date)
 
         val serializer = serializer<TestClass>()
         val data = mapOf<String, Any?>(
diff --git a/firestore/src/test/java/de/sipgate/federmappe/firestore/FirebaseTimestampTests.kt b/firestore/src/test/java/de/sipgate/federmappe/firestore/FirebaseTimestampTests.kt
index 6e8b747..10b0f9c 100644
--- a/firestore/src/test/java/de/sipgate/federmappe/firestore/FirebaseTimestampTests.kt
+++ b/firestore/src/test/java/de/sipgate/federmappe/firestore/FirebaseTimestampTests.kt
@@ -2,7 +2,7 @@ package de.sipgate.federmappe.firestore
 
 import com.google.firebase.Timestamp
 import de.sipgate.federmappe.common.StringMapToObjectDecoder
-import de.sipgate.federmappe.common.serializers.TimestampSerializer
+import de.sipgate.federmappe.common.serializers.TimestampToDateSerializer
 import java.util.Date
 import java.util.GregorianCalendar
 import kotlinx.serialization.Contextual
@@ -36,7 +36,7 @@ class FirebaseTimestampTests {
                 StringMapToObjectDecoder(
                     data,
                     ignoreUnknownProperties = true,
-                    serializersModule = SerializersModule { contextual(TimestampSerializer) },
+                    serializersModule = SerializersModule { contextual(TimestampToDateSerializer) },
                     subtypeDecoder = { (it as? Timestamp)?.let(::FirebaseTimestampDecoder) }
                 ),
             )
@@ -51,7 +51,7 @@ class FirebaseTimestampTests {
         // Arrange
         @Serializable
         data class TestClass(
-            @Serializable(with = TimestampSerializer::class) val a: Date,
+            @Serializable(with = TimestampToDateSerializer::class) val a: Date,
         )
 
         val serializer = serializer<TestClass>()
@@ -95,7 +95,7 @@ class FirebaseTimestampTests {
                 StringMapToObjectDecoder(
                     data,
                     ignoreUnknownProperties = true,
-                    serializersModule = SerializersModule { contextual(TimestampSerializer) },
+                    serializersModule = SerializersModule { contextual(TimestampToDateSerializer) },
                     subtypeDecoder = { (it as? Timestamp)?.let(::FirebaseTimestampDecoder) }
                 ),
             )
@@ -125,7 +125,7 @@ class FirebaseTimestampTests {
                 StringMapToObjectDecoder(
                     data,
                     ignoreUnknownProperties = true,
-                    serializersModule = SerializersModule { contextual(TimestampSerializer) },
+                    serializersModule = SerializersModule { contextual(TimestampToDateSerializer) },
                 ),
             )
 
@@ -157,7 +157,7 @@ class FirebaseTimestampTests {
                 StringMapToObjectDecoder(
                     data,
                     ignoreUnknownProperties = true,
-                    serializersModule = SerializersModule { contextual(TimestampSerializer) },
+                    serializersModule = SerializersModule { contextual(TimestampToDateSerializer) },
                     subtypeDecoder = { (it as? Timestamp)?.let(::FirebaseTimestampDecoder) }
                 ),
             )
diff --git a/firestore/src/test/java/de/sipgate/federmappe/firestore/serializers/TimestampSerializerTest.kt b/firestore/src/test/java/de/sipgate/federmappe/firestore/serializers/TimestampToDateSerializerTest.kt
similarity index 89%
rename from firestore/src/test/java/de/sipgate/federmappe/firestore/serializers/TimestampSerializerTest.kt
rename to firestore/src/test/java/de/sipgate/federmappe/firestore/serializers/TimestampToDateSerializerTest.kt
index 2465b4d..fd41fd6 100644
--- a/firestore/src/test/java/de/sipgate/federmappe/firestore/serializers/TimestampSerializerTest.kt
+++ b/firestore/src/test/java/de/sipgate/federmappe/firestore/serializers/TimestampToDateSerializerTest.kt
@@ -3,7 +3,7 @@ package de.sipgate.federmappe.firestore.serializers
 import com.google.firebase.Timestamp
 import de.sipgate.federmappe.firestore.FirebaseTimestampDecoder
 import de.sipgate.federmappe.common.StringMapToObjectDecoder
-import de.sipgate.federmappe.common.serializers.TimestampSerializer
+import de.sipgate.federmappe.common.serializers.TimestampToDateSerializer
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.serializer
@@ -12,7 +12,7 @@ import org.junit.jupiter.api.Test
 import java.util.Date
 
 
-class TimestampSerializerTest {
+class TimestampToDateSerializerTest {
     private val epochSeconds = 1707833611L * 1000
     private val nanos = 801 / 1000000
 
@@ -23,7 +23,7 @@ class TimestampSerializerTest {
     @Test
     fun testDeserialization() {
         @Serializable
-        data class TestClass(val a: @Serializable(with = TimestampSerializer::class) Date)
+        data class TestClass(val a: @Serializable(with = TimestampToDateSerializer::class) Date)
 
         val serializer = serializer<TestClass>()
         val data = mapOf<String, Any?>("a" to Timestamp(1707833611, 801))