diff --git a/backend/build.gradle.kts b/backend/build.gradle.kts
index 9e6f4026dbf3d143026208d61ca30adf94f75436..ccd63947a4d48430d4016545e7256dfd35c27fb2 100644
--- a/backend/build.gradle.kts
+++ b/backend/build.gradle.kts
@@ -37,4 +37,5 @@ dependencies {
     testImplementation("io.ktor:ktor-server-tests:$ktor_version")
     testImplementation("org.jetbrains.kotlin:kotlin-test-junit:$kotlin_version")
     implementation("com.google.code.gson:gson:2.8.9")
+    implementation("org.jetbrains.kotlinx:kotlinx-datetime:0.3.2")
 }
\ No newline at end of file
diff --git a/backend/src/main/kotlin/space/rethelyi/model/Floor.kt b/backend/src/main/kotlin/space/rethelyi/model/Floor.kt
index 59203f775c93bd0831dfa1fbc4b0d023677db64e..e43dcaa252b75e85a1ae70f9cc44c9a6093f1930 100644
--- a/backend/src/main/kotlin/space/rethelyi/model/Floor.kt
+++ b/backend/src/main/kotlin/space/rethelyi/model/Floor.kt
@@ -21,6 +21,6 @@ fun Floor.toResponseV1(): FloorDataOld {
     return FloorDataOld(
         id = id,
         machines = oldMachineData,
-        last_query_time = machines.last().lastQueryTime.toInstant().toString(),
+        last_query_time = machines.last().lastQueryTime.toString(),
     )
 }
\ No newline at end of file
diff --git a/backend/src/main/kotlin/space/rethelyi/model/Machine.kt b/backend/src/main/kotlin/space/rethelyi/model/Machine.kt
index e88125364921edf65b0bc5ef82123ca9173f6b98..abe86f9f2683951564ecfb6819f128376412366e 100644
--- a/backend/src/main/kotlin/space/rethelyi/model/Machine.kt
+++ b/backend/src/main/kotlin/space/rethelyi/model/Machine.kt
@@ -1,5 +1,7 @@
 package space.rethelyi.model
 
+import kotlinx.datetime.Clock
+import kotlinx.datetime.Instant
 import space.rethelyi.model.response.MachineData
 import space.rethelyi.model.response.MachineDataOld
 import java.util.*
@@ -9,7 +11,8 @@ data class Machine(
     var id: Int = 0,
     var kindOf: Kind = Kind.Unknown,
     var status: Status = Status.LostInSpace,
-    var lastQueryTime: Date = Date(),
+    var lastQueryTime: Instant = Clock.System.now(),
+    var lastChanged: Instant = Clock.System.now(),
     val power: MutableList<Int> = mutableListOf(),
     val threshold: Int = 200
 )
@@ -43,7 +46,7 @@ fun Machine.addPower(newPower: Int) {
         power -= power.first()
     }
 
-    lastQueryTime = Date()
+    lastQueryTime = Clock.System.now()
 }
 
 fun Machine.toResponseV2(): MachineData {
@@ -52,7 +55,7 @@ fun Machine.toResponseV2(): MachineData {
         kindOf = kindOf,
         status = status,
         lastQueryTime = lastQueryTime.toString(),
-        unixTimeStamp = lastQueryTime.toInstant().toEpochMilli()
+        lastChanged = lastChanged.toString(),
     )
 }
 
diff --git a/backend/src/main/kotlin/space/rethelyi/model/response/FloorDataOld.kt b/backend/src/main/kotlin/space/rethelyi/model/response/FloorDataOld.kt
index 8fd2c5add1bc9b0be2a4dfc5ea133e9b996cc7cd..21f66f1f97115276e43c2a9aa6a697b00ef55a91 100644
--- a/backend/src/main/kotlin/space/rethelyi/model/response/FloorDataOld.kt
+++ b/backend/src/main/kotlin/space/rethelyi/model/response/FloorDataOld.kt
@@ -7,5 +7,5 @@ import java.util.*
 data class FloorDataOld(
     var id: Int = 0,
     var machines: List<MachineDataOld> = listOf(),
-    var last_query_time: String = Date().toString(),
+    var last_query_time: String = "",
 )
\ No newline at end of file
diff --git a/backend/src/main/kotlin/space/rethelyi/model/response/MachineData.kt b/backend/src/main/kotlin/space/rethelyi/model/response/MachineData.kt
index 0f80fa83b0f830fb149497e283c62e7ab06040eb..236b2f58ed388d0f61f217048a3184b8b09ec8b8 100644
--- a/backend/src/main/kotlin/space/rethelyi/model/response/MachineData.kt
+++ b/backend/src/main/kotlin/space/rethelyi/model/response/MachineData.kt
@@ -10,6 +10,6 @@ data class MachineData(
     var id: Int = 0,
     var kindOf: Kind = Kind.Unknown,
     var status: Status = Status.LostInSpace,
-    var lastQueryTime: String = Date().toString(),
-    var unixTimeStamp: Long = 0
+    var lastQueryTime: String = "",
+    var lastChanged: String = "",
 )