diff --git a/mirai-core-qqandroid/src/commonMain/kotlin/net/mamoe/mirai/qqandroid/contact/QQImpl.kt b/mirai-core-qqandroid/src/commonMain/kotlin/net/mamoe/mirai/qqandroid/contact/QQImpl.kt
index 41e34dc16..e142ced00 100644
--- a/mirai-core-qqandroid/src/commonMain/kotlin/net/mamoe/mirai/qqandroid/contact/QQImpl.kt
+++ b/mirai-core-qqandroid/src/commonMain/kotlin/net/mamoe/mirai/qqandroid/contact/QQImpl.kt
@@ -66,7 +66,7 @@ internal class QQImpl(
     override val id: Long,
     private val friendInfo: FriendInfo
 ) : QQ() {
-    var lastMessageSequence: AtomicInt = atomic(-1)
+    val lastMessageSequence: AtomicInt = atomic(-1)
 
     override val bot: QQAndroidBot by bot.unsafeWeakRef()
     override val nick: String