diff --git a/kotlin-native/runtime/src/gc/cms/cpp/Barriers.cpp b/kotlin-native/runtime/src/gc/cms/cpp/Barriers.cpp
index 7c40dfac8c0..54d7ed49b76 100644
--- a/kotlin-native/runtime/src/gc/cms/cpp/Barriers.cpp
+++ b/kotlin-native/runtime/src/gc/cms/cpp/Barriers.cpp
@@ -68,8 +68,7 @@ ALWAYS_INLINE void gc::BarriersThreadData::onAllocation(ObjHeader* allocated) {
         RuntimeAssert(shouldMark == barriersEnabled, "New allocations marking must happen with and only with weak ref barriers");
         if (shouldMark) {
             auto& objectData = alloc::objectDataForObject(allocated);
-            bool wasUnmarked = objectData.tryMark();
-            RuntimeAssert(wasUnmarked, "No one else could mark this newly allocated object before");
+            objectData.markUncontended();
             markHandle_->addObject();
         }
     }
diff --git a/kotlin-native/runtime/src/gc/cms/cpp/ObjectData.hpp b/kotlin-native/runtime/src/gc/cms/cpp/ObjectData.hpp
index 72a9e871ebc..f1cbe7b77f5 100644
--- a/kotlin-native/runtime/src/gc/cms/cpp/ObjectData.hpp
+++ b/kotlin-native/runtime/src/gc/cms/cpp/ObjectData.hpp
@@ -16,8 +16,16 @@
 namespace kotlin::gc {
 
 class GC::ObjectData {
+    static constexpr intptr_t kNoQueueMark = 1;
 public:
-    bool tryMark() noexcept { return trySetNext(reinterpret_cast<ObjectData*>(1)); }
+    bool tryMark() noexcept { return trySetNext(reinterpret_cast<ObjectData*>(kNoQueueMark)); }
+
+    void markUncontended() noexcept {
+        RuntimeAssert(!marked(), "Must not be marked previously");
+        auto nextVal = reinterpret_cast<ObjectData*>(kNoQueueMark);
+        setNext(nextVal);
+        RuntimeAssert(next() == nextVal, "Non-atomic marking must not be contended");
+    }
 
     bool marked() const noexcept { return next() != nullptr; }