diff --git a/ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/PlaybackStateSerializer.kt b/ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/PlaybackStateSerializer.kt
index f32bc6b7..c74254bd 100644
--- a/ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/PlaybackStateSerializer.kt
+++ b/ultrasonic/src/main/kotlin/org/moire/ultrasonic/service/PlaybackStateSerializer.kt
@@ -33,7 +33,7 @@ class PlaybackStateSerializer : KoinComponent {
     private val mediaSessionHandler by inject<MediaSessionHandler>()
 
     val lock: Lock = ReentrantLock()
-    val setup = AtomicBoolean(false)
+    private val setup = AtomicBoolean(false)
 
     private val appScope = CoroutineScope(SupervisorJob() + Dispatchers.IO)