diff --git a/firestore/src/androidTest/kotlin/de/sipgate/federmappe/firestore/integration/FirestoreIntegrationTest.kt b/firestore/src/androidTest/kotlin/de/sipgate/federmappe/firestore/integration/FirestoreIntegrationTest.kt
index 261504e..a38702c 100644
--- a/firestore/src/androidTest/kotlin/de/sipgate/federmappe/firestore/integration/FirestoreIntegrationTest.kt
+++ b/firestore/src/androidTest/kotlin/de/sipgate/federmappe/firestore/integration/FirestoreIntegrationTest.kt
@@ -50,10 +50,13 @@ class FirestoreIntegrationTest {
         @JvmStatic
         fun initializeTestData(): Unit = runTest {
             val users = firestore.collection("$tempNamespace-users")
-            val root = users.add(mapOf<String, Any?>(
-                "name" to "root",
-                "createdAt" to Timestamp(1720794610L, 0),
-            )).await()
+            val root = users.add(
+                mapOf<String, Any?>(
+                    "name" to "root",
+                    "createdAt" to Timestamp(1720794610L, 0),
+                    "nested" to mapOf<String, Any?>("updatedAt" to Timestamp(1720794610L, 0))
+                )
+            ).await()
             root.update("id", root.id).await()
         }
     }
@@ -100,6 +103,6 @@ class FirestoreIntegrationTest {
             }
         }
         assertTrue(b.isNotEmpty())
-        assertIs< Entity.FullUser>(b.first())
+        assertIs<Entity.FullUser>(b.first())
     }
 }
diff --git a/firestore/src/main/java/de/sipgate/federmappe/firestore/QuerySnapshotExt.kt b/firestore/src/main/java/de/sipgate/federmappe/firestore/QuerySnapshotExt.kt
index 24406dc..e39c046 100644
--- a/firestore/src/main/java/de/sipgate/federmappe/firestore/QuerySnapshotExt.kt
+++ b/firestore/src/main/java/de/sipgate/federmappe/firestore/QuerySnapshotExt.kt
@@ -25,16 +25,20 @@ inline fun <reified T : Any> QuerySnapshot.toObjects(
     }
 }
 
+@Suppress("UNCHECKED_CAST")
 fun Map<String, Any>.normalizeStringMap(): Map<String, Any> = mapValues {
     when (val value = it.value) {
         is Timestamp -> value.toDecodableTimestamp()
+        is Map<*, *> -> (value as? Map<String, Any>)?.normalizeStringMap() ?: value
         else -> value
     }
 }
 
+@Suppress("UNCHECKED_CAST")
 fun Map<String, Any?>.normalizeStringMapNullable(): Map<String, Any?> = mapValues {
     when (val value = it.value) {
         is Timestamp -> value.toDecodableTimestamp()
+        is Map<*, *> -> (value as? Map<String, Any>)?.normalizeStringMap() ?: value
         else -> value
     }
 }
diff --git a/firestore/src/test/kotlin/de/sipgate/federmappe/firestore/types/FirestoreTimestampToDecodableTimestampTest.kt b/firestore/src/test/kotlin/de/sipgate/federmappe/firestore/types/FirestoreTimestampToDecodableTimestampTest.kt
index ae0f257..f530a3c 100644
--- a/firestore/src/test/kotlin/de/sipgate/federmappe/firestore/types/FirestoreTimestampToDecodableTimestampTest.kt
+++ b/firestore/src/test/kotlin/de/sipgate/federmappe/firestore/types/FirestoreTimestampToDecodableTimestampTest.kt
@@ -2,6 +2,8 @@ package de.sipgate.federmappe.firestore.types
 
 import com.google.firebase.Timestamp
 import de.sipgate.federmappe.common.decoder.StringMapToObjectDecoder
+import de.sipgate.federmappe.firestore.normalizeStringMap
+import de.sipgate.federmappe.firestore.normalizeStringMapNullable
 import kotlinx.datetime.Instant
 import kotlinx.datetime.serializers.InstantComponentSerializer
 import kotlinx.datetime.toJavaInstant
@@ -137,4 +139,82 @@ class FirestoreTimestampToDecodableTimestampTest {
         assertEquals(null, result.createdAt)
         assertIs<MockLocalDataClass>(result)
     }
+
+    @OptIn(ExperimentalSerializationApi::class)
+    @Test
+    fun nestedFirestoreTimestampIsNormalizedAndDecodedToKotlinInstantCorrectly() {
+        // Arrange
+        val expectedInstant = Instant.fromEpochSeconds(1716823455)
+        val expectedDate = Date.from(expectedInstant.toJavaInstant())
+        val timestamp = Timestamp(expectedDate)
+
+        @Serializable
+        data class MockNestedDataClass(
+            @Contextual
+            val createdAt: Instant
+        )
+
+        @Serializable
+        data class MockLocalDataClass(
+            @Contextual
+            val nested: MockNestedDataClass
+        )
+
+        val serializer = serializer<MockLocalDataClass>()
+
+        val data =
+            mapOf<String, Any>("nested" to mapOf<String, Any>("createdAt" to timestamp)).normalizeStringMap()
+
+        // Act
+        val result =
+            serializer.deserialize(
+                StringMapToObjectDecoder(
+                    data = data,
+                    serializersModule = SerializersModule { contextual(InstantComponentSerializer) },
+                ),
+            )
+
+        // Assert
+        assertEquals(expectedInstant, result.nested.createdAt)
+        assertIs<MockLocalDataClass>(result)
+    }
+
+    @OptIn(ExperimentalSerializationApi::class)
+    @Test
+    fun nestedFirestoreTimestampIsNormalizedAndDecodedToKotlinInstantCorrectlyNullable() {
+        // Arrange
+        val expectedInstant = Instant.fromEpochSeconds(1716823455)
+        val expectedDate = Date.from(expectedInstant.toJavaInstant())
+        val timestamp = Timestamp(expectedDate)
+
+        @Serializable
+        data class MockNestedDataClass(
+            @Contextual
+            val createdAt: Instant
+        )
+
+        @Serializable
+        data class MockLocalDataClass(
+            @Contextual
+            val nested: MockNestedDataClass
+        )
+
+        val serializer = serializer<MockLocalDataClass>()
+
+        val data =
+            mapOf<String, Any?>("nested" to mapOf<String, Any?>("createdAt" to timestamp)).normalizeStringMapNullable()
+
+        // Act
+        val result =
+            serializer.deserialize(
+                StringMapToObjectDecoder(
+                    data = data,
+                    serializersModule = SerializersModule { contextual(InstantComponentSerializer) },
+                ),
+            )
+
+        // Assert
+        assertEquals(expectedInstant, result.nested.createdAt)
+        assertIs<MockLocalDataClass>(result)
+    }
 }