diff --git a/kotlin-native/backend.native/tests/objcexport/values.swift b/kotlin-native/backend.native/tests/objcexport/values.swift
index 297611283b1..6f1bd508216 100644
--- a/kotlin-native/backend.native/tests/objcexport/values.swift
+++ b/kotlin-native/backend.native/tests/objcexport/values.swift
@@ -596,17 +596,10 @@ func testShared() throws {
         try assertFalse(ValuesKt.isFrozen(obj: obj), "isFrozen(\(obj))")
     }
 
-    if ValuesKt.isExperimentalMM {
-        try assertNotFrozen(NSObject())
-        try assertNotFrozen(TestSharedIImpl())
-        try assertNotFrozen(ValuesKt.kotlinLambda(block: { return $0 }) as AnyObject)
-        try assertNotFrozen(FinalClassExtOpen())
-    } else {
-        try assertFrozen(NSObject())
-        try assertFrozen(TestSharedIImpl())
-        try assertFrozen(ValuesKt.kotlinLambda(block: { return $0 }) as AnyObject)
-        try assertNotFrozen(FinalClassExtOpen())
-    }
+    try assertFrozen(NSObject())
+    try assertFrozen(TestSharedIImpl())
+    try assertFrozen(ValuesKt.kotlinLambda(block: { return $0 }) as AnyObject)
+    try assertNotFrozen(FinalClassExtOpen())
 }
 
 class PureSwiftClass {
diff --git a/kotlin-native/backend.native/tests/runtime/workers/freeze2.kt b/kotlin-native/backend.native/tests/runtime/workers/freeze2.kt
index 0bb2be40ef4..7fb53594c04 100644
--- a/kotlin-native/backend.native/tests/runtime/workers/freeze2.kt
+++ b/kotlin-native/backend.native/tests/runtime/workers/freeze2.kt
@@ -59,36 +59,27 @@ data class Data(var int: Int)
     assertFailsWith<InvalidMutabilityException> { a8[1] = 2.0 }
 
     // Ensure that String and integral boxes are frozen by default, by passing local to the worker.
-    val hasToBeFrozen = Platform.memoryModel == MemoryModel.STRICT
     val worker = Worker.start()
     var data: Any = "Hello" + " " + "world"
-    if (hasToBeFrozen) {
-        assertTrue(data.isFrozen)
-    }
+    assertTrue(data.isFrozen)
     worker.execute(TransferMode.SAFE, { data } ) {
         input -> println("Worker 1: $input")
     }.result
 
     data = 42
-    if (hasToBeFrozen) {
-        assertTrue(data.isFrozen)
-    }
+    assertTrue(data.isFrozen)
     worker.execute(TransferMode.SAFE, { data } ) {
         input -> println("Worker2: $input")
     }.result
 
     data = 239.0
-    if (hasToBeFrozen) {
-        assertTrue(data.isFrozen)
-    }
+    assertTrue(data.isFrozen)
     worker.execute(TransferMode.SAFE, { data } ) {
         input -> println("Worker3: $input")
     }.result
 
     data = 'a'
-    if (hasToBeFrozen) {
-        assertTrue(data.isFrozen)
-    }
+    assertTrue(data.isFrozen)
     worker.execute(TransferMode.SAFE, { data } ) {
         input -> println("Worker4: $input")
     }.result
diff --git a/kotlin-native/runtime/src/main/cpp/Atomic.cpp b/kotlin-native/runtime/src/main/cpp/Atomic.cpp
index 5f059b8a956..f1f550fd83d 100644
--- a/kotlin-native/runtime/src/main/cpp/Atomic.cpp
+++ b/kotlin-native/runtime/src/main/cpp/Atomic.cpp
@@ -182,7 +182,9 @@ void Kotlin_AtomicReference_checkIfFrozen(KRef value) {
 }
 
 OBJ_GETTER(Kotlin_AtomicReference_compareAndSwap, KRef thiz, KRef expectedValue, KRef newValue) {
-    Kotlin_AtomicReference_checkIfFrozen(newValue);
+    if (isPermanentOrFrozen(thiz)) {
+        Kotlin_AtomicReference_checkIfFrozen(newValue);
+    }
     // See Kotlin_AtomicReference_get() for explanations, why locking is needed.
     AtomicReferenceLayout* ref = asAtomicReference(thiz);
     RETURN_RESULT_OF(SwapHeapRefLocked, &ref->value_, expectedValue, newValue,
@@ -190,7 +192,9 @@ OBJ_GETTER(Kotlin_AtomicReference_compareAndSwap, KRef thiz, KRef expectedValue,
 }
 
 KBoolean Kotlin_AtomicReference_compareAndSet(KRef thiz, KRef expectedValue, KRef newValue) {
-    Kotlin_AtomicReference_checkIfFrozen(newValue);
+    if (isPermanentOrFrozen(thiz)) {
+        Kotlin_AtomicReference_checkIfFrozen(newValue);
+    }
     // See Kotlin_AtomicReference_get() for explanations, why locking is needed.
     AtomicReferenceLayout* ref = asAtomicReference(thiz);
     ObjHolder holder;
@@ -200,7 +204,9 @@ KBoolean Kotlin_AtomicReference_compareAndSet(KRef thiz, KRef expectedValue, KRe
 }
 
 void Kotlin_AtomicReference_set(KRef thiz, KRef newValue) {
-    Kotlin_AtomicReference_checkIfFrozen(newValue);
+    if (isPermanentOrFrozen(thiz)) {
+        Kotlin_AtomicReference_checkIfFrozen(newValue);
+    }
     AtomicReferenceLayout* ref = asAtomicReference(thiz);
     SetHeapRefLocked(&ref->value_, newValue, &ref->lock_, &ref->cookie_);
 }
diff --git a/kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/Atomics.kt b/kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/Atomics.kt
index 62605702847..e988df5ccec 100644
--- a/kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/Atomics.kt
+++ b/kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/Atomics.kt
@@ -326,7 +326,7 @@ public class FreezableAtomicReference<T>(private var value_: T) {
     public var value: T
         get() = @Suppress("UNCHECKED_CAST")(getImpl() as T)
         set(new) {
-            if (this.isFrozen)
+            if (this.isShareable())
                 setImpl(new)
             else
                 value_ = new
@@ -342,7 +342,9 @@ public class FreezableAtomicReference<T>(private var value_: T) {
      * @return the old value
      */
      public fun compareAndSwap(expected: T, new: T): T {
-        return if (this.isFrozen) @Suppress("UNCHECKED_CAST")(compareAndSwapImpl(expected, new) as T) else {
+        return if (this.isShareable()) {
+            @Suppress("UNCHECKED_CAST")(compareAndSwapImpl(expected, new) as T)
+        } else {
             val old = value_
             if (old === expected) value_ = new
             old
@@ -358,7 +360,8 @@ public class FreezableAtomicReference<T>(private var value_: T) {
      * @return true if successful
      */
     public fun compareAndSet(expected: T, new: T): Boolean {
-        if (this.isFrozen) return compareAndSetImpl(expected, new)
+        if (this.isShareable())
+            return compareAndSetImpl(expected, new)
         val old = value_
         if (old === expected) {
             value_ = new
diff --git a/kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/Internal.kt b/kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/Internal.kt
index 302e01a2418..d54ab2818ec 100644
--- a/kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/Internal.kt
+++ b/kotlin-native/runtime/src/main/kotlin/kotlin/native/concurrent/Internal.kt
@@ -14,6 +14,9 @@ import kotlin.native.identityHashCode
 import kotlin.reflect.KClass
 import kotlinx.cinterop.*
 
+@GCUnsafeCall("Kotlin_Any_isShareable")
+external internal fun Any?.isShareable(): Boolean
+
 // Implementation details.
 
 @GCUnsafeCall("Kotlin_Worker_stateOfFuture")
diff --git a/kotlin-native/runtime/src/main/kotlin/kotlin/native/internal/Cleaner.kt b/kotlin-native/runtime/src/main/kotlin/kotlin/native/internal/Cleaner.kt
index fbeed01a169..59799524924 100644
--- a/kotlin-native/runtime/src/main/kotlin/kotlin/native/internal/Cleaner.kt
+++ b/kotlin-native/runtime/src/main/kotlin/kotlin/native/internal/Cleaner.kt
@@ -125,8 +125,5 @@ private class CleanerImpl(
     private val cleanPtr: NativePtr,
 ): Cleaner {}
 
-@GCUnsafeCall("Kotlin_Any_isShareable")
-external private fun Any?.isShareable(): Boolean
-
 @GCUnsafeCall("CreateStablePointer")
 external private fun createStablePointer(obj: Any): NativePtr
diff --git a/kotlin-native/runtime/src/mm/cpp/Memory.cpp b/kotlin-native/runtime/src/mm/cpp/Memory.cpp
index cc3b253c31e..98c4f49fcd4 100644
--- a/kotlin-native/runtime/src/mm/cpp/Memory.cpp
+++ b/kotlin-native/runtime/src/mm/cpp/Memory.cpp
@@ -82,7 +82,8 @@ void ObjHeader::destroyMetaObject(ObjHeader* object) {
 }
 
 ALWAYS_INLINE bool isPermanentOrFrozen(const ObjHeader* obj) {
-    return mm::IsFrozen(obj);
+    // TODO: Freeze TF_IMMUTABLE objects upon creation.
+    return mm::IsFrozen(obj) || ((obj->type_info()->flags_ & TF_IMMUTABLE) != 0);
 }
 
 ALWAYS_INLINE bool isShareable(const ObjHeader* obj) {