diff --git a/kotlin-native/backend.native/tests/runtime/basic/cleaner_workers.kt b/kotlin-native/backend.native/tests/runtime/basic/cleaner_workers.kt
index a5c4f573df9..3b759c92d24 100644
--- a/kotlin-native/backend.native/tests/runtime/basic/cleaner_workers.kt
+++ b/kotlin-native/backend.native/tests/runtime/basic/cleaner_workers.kt
@@ -2,7 +2,7 @@
  * Copyright 2010-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
  * that can be found in the LICENSE file.
  */
-@file:OptIn(ExperimentalStdlibApi::class, FreezingIsDeprecated::class)
+@file:OptIn(ExperimentalStdlibApi::class, FreezingIsDeprecated::class, kotlin.experimental.ExperimentalNativeApi::class)
 
 package runtime.basic.cleaner_workers
 
diff --git a/kotlin-native/backend.native/tests/runtime/memory/cycles1.kt b/kotlin-native/backend.native/tests/runtime/memory/cycles1.kt
index ae7572e7b0b..9dc33eaee60 100644
--- a/kotlin-native/backend.native/tests/runtime/memory/cycles1.kt
+++ b/kotlin-native/backend.native/tests/runtime/memory/cycles1.kt
@@ -3,6 +3,8 @@
  * that can be found in the LICENSE file.
  */
 
+@file:OptIn(kotlin.experimental.ExperimentalNativeApi::class)
+
 package runtime.memory.cycles1
 
 import kotlin.test.*
diff --git a/kotlin-native/backend.native/tests/runtime/memory/weak0.kt b/kotlin-native/backend.native/tests/runtime/memory/weak0.kt
index b0eac53d4e3..0c8cecfac21 100644
--- a/kotlin-native/backend.native/tests/runtime/memory/weak0.kt
+++ b/kotlin-native/backend.native/tests/runtime/memory/weak0.kt
@@ -3,6 +3,8 @@
  * that can be found in the LICENSE file.
  */
 
+@file:OptIn(kotlin.experimental.ExperimentalNativeApi::class)
+
 package runtime.memory.weak0
 
 import kotlin.test.*
diff --git a/kotlin-native/backend.native/tests/runtime/memory/weak1.kt b/kotlin-native/backend.native/tests/runtime/memory/weak1.kt
index 57dffc65550..754dd2ef368 100644
--- a/kotlin-native/backend.native/tests/runtime/memory/weak1.kt
+++ b/kotlin-native/backend.native/tests/runtime/memory/weak1.kt
@@ -3,6 +3,8 @@
  * that can be found in the LICENSE file.
  */
 
+@file:OptIn(kotlin.experimental.ExperimentalNativeApi::class)
+
 package runtime.memory.weak1
 
 import kotlin.test.*
diff --git a/kotlin-native/backend.native/tests/runtime/workers/worker10.kt b/kotlin-native/backend.native/tests/runtime/workers/worker10.kt
index 5fd7b72ce4e..8124defb8e3 100644
--- a/kotlin-native/backend.native/tests/runtime/workers/worker10.kt
+++ b/kotlin-native/backend.native/tests/runtime/workers/worker10.kt
@@ -1,4 +1,4 @@
-@file:OptIn(FreezingIsDeprecated::class)
+@file:OptIn(FreezingIsDeprecated::class, kotlin.experimental.ExperimentalNativeApi::class)
 package runtime.workers.worker10
 
 import kotlin.test.*
diff --git a/kotlin-native/runtime/src/main/kotlin/kotlin/native/ref/Weak.kt b/kotlin-native/runtime/src/main/kotlin/kotlin/native/ref/Weak.kt
index 3192c5022d4..b97e034021e 100644
--- a/kotlin-native/runtime/src/main/kotlin/kotlin/native/ref/Weak.kt
+++ b/kotlin-native/runtime/src/main/kotlin/kotlin/native/ref/Weak.kt
@@ -5,11 +5,14 @@
 
 package kotlin.native.ref
 
+import kotlin.experimental.ExperimentalNativeApi
+
 /**
  * Class WeakReference encapsulates weak reference to an object, which could be used to either
  * retrieve a strong reference to an object, or return null, if object was already destroyed by
  * the memory manager.
  */
+@ExperimentalNativeApi
 public class WeakReference<T : Any> {
     /**
      * Creates a weak reference object pointing to an object. Weak reference doesn't prevent