diff --git a/kotlin-native/runtime/src/gc/common/cpp/MarkAndSweepUtils.hpp b/kotlin-native/runtime/src/gc/common/cpp/MarkAndSweepUtils.hpp
index 48b73075c09..dbb67c3b365 100644
--- a/kotlin-native/runtime/src/gc/common/cpp/MarkAndSweepUtils.hpp
+++ b/kotlin-native/runtime/src/gc/common/cpp/MarkAndSweepUtils.hpp
@@ -69,10 +69,11 @@ void SweepExtraObjects(typename Traits::ExtraObjectsFactory& objectFactory) noex
     auto iter = objectFactory.LockForIter();
     for (auto it = iter.begin(); it != iter.end();) {
         auto &extraObject = *it;
-        if (!Traits::IsMarkedByExtraObject(extraObject)) {
+        if (!extraObject.getFlag(mm::ExtraObjectData::FLAGS_IN_FINALIZER_QUEUE) && !Traits::IsMarkedByExtraObject(extraObject)) {
             extraObject.ClearWeakReferenceCounter();
             if (extraObject.HasAssociatedObject()) {
                 extraObject.DetachAssociatedObject();
+                extraObject.setFlag(mm::ExtraObjectData::FLAGS_IN_FINALIZER_QUEUE);
                 ++it;
             } else {
                 extraObject.Uninstall();
diff --git a/kotlin-native/runtime/src/mm/cpp/ExtraObjectData.hpp b/kotlin-native/runtime/src/mm/cpp/ExtraObjectData.hpp
index 982891b51d2..0714954a888 100644
--- a/kotlin-native/runtime/src/mm/cpp/ExtraObjectData.hpp
+++ b/kotlin-native/runtime/src/mm/cpp/ExtraObjectData.hpp
@@ -23,10 +23,11 @@ namespace mm {
 // Optional data that's lazily allocated only for objects that need it.
 class ExtraObjectData : private Pinned, public KonanAllocatorAware {
 public:
+    // flags are stored as single atomic uint32, values are bit numbers in that uint32
     enum Flags : uint32_t {
-        FLAGS_NONE = 0,
-        FLAGS_FROZEN = 1 << 0,
-        FLAGS_NEVER_FROZEN = 1 << 1,
+        FLAGS_FROZEN = 0,
+        FLAGS_NEVER_FROZEN = 1,
+        FLAGS_IN_FINALIZER_QUEUE = 2,
     };
 
     static constexpr unsigned WEAK_REF_TAG = 1;
@@ -49,7 +50,9 @@ public:
     bool HasAssociatedObject() noexcept;
     void DetachAssociatedObject() noexcept;
 
-    std::atomic<Flags>& flags() noexcept { return flags_; }
+    bool getFlag(Flags value) noexcept { return (flags_.load() & (1u << static_cast<uint32_t>(value))) != 0; }
+    void setFlag(Flags value) noexcept { flags_.fetch_or(1u << static_cast<uint32_t>(value)); }
+
 
     bool HasWeakReferenceCounter() noexcept { return hasPointerBits(weakReferenceCounterOrBaseObject_.load(), WEAK_REF_TAG); }
     void ClearWeakReferenceCounter() noexcept;
@@ -84,7 +87,7 @@ private:
     // Must be first to match `TypeInfo` layout.
     const TypeInfo* typeInfo_;
 
-    std::atomic<Flags> flags_ = FLAGS_NONE;
+    std::atomic<uint32_t> flags_ = 0;
 
 #ifdef KONAN_OBJC_INTEROP
     void* associatedObject_ = nullptr;
diff --git a/kotlin-native/runtime/src/mm/cpp/Freezing.cpp b/kotlin-native/runtime/src/mm/cpp/Freezing.cpp
index f696f510902..6c8ecfd2287 100644
--- a/kotlin-native/runtime/src/mm/cpp/Freezing.cpp
+++ b/kotlin-native/runtime/src/mm/cpp/Freezing.cpp
@@ -20,7 +20,7 @@ bool mm::IsFrozen(const ObjHeader* object) noexcept {
     }
 
     if (auto* extraObjectData = mm::ExtraObjectData::Get(object)) {
-        return (extraObjectData->flags() & mm::ExtraObjectData::FLAGS_FROZEN) != 0;
+        return extraObjectData->getFlag(mm::ExtraObjectData::FLAGS_FROZEN);
     }
     return false;
 }
@@ -48,12 +48,13 @@ ObjHeader* mm::FreezeSubgraph(ObjHeader* root) noexcept {
     }
     for (auto* object : objects) {
         if (auto* extraObjectData = mm::ExtraObjectData::Get(object)) {
-            if ((extraObjectData->flags() & mm::ExtraObjectData::FLAGS_NEVER_FROZEN) != 0) return object;
+            if (extraObjectData->getFlag(mm::ExtraObjectData::FLAGS_NEVER_FROZEN)) {
+                return object;
+            }
         }
     }
     for (auto* object : objects) {
-        auto& flags = mm::ExtraObjectData::GetOrInstall(object).flags();
-        flags = static_cast<mm::ExtraObjectData::Flags>(flags | mm::ExtraObjectData::FLAGS_FROZEN);
+        mm::ExtraObjectData::GetOrInstall(object).setFlag(mm::ExtraObjectData::FLAGS_FROZEN);
     }
     return nullptr;
 }
@@ -63,7 +64,6 @@ bool mm::EnsureNeverFrozen(ObjHeader* object) noexcept {
         return false;
     }
 
-    auto& flags = mm::ExtraObjectData::GetOrInstall(object).flags();
-    flags = static_cast<mm::ExtraObjectData::Flags>(flags | mm::ExtraObjectData::FLAGS_NEVER_FROZEN);
+    mm::ExtraObjectData::GetOrInstall(object).setFlag(mm::ExtraObjectData::FLAGS_NEVER_FROZEN);
     return true;
 }