diff --git a/src/hotspot/share/gc/shenandoah/shenandoahLock.hpp b/src/hotspot/share/gc/shenandoah/shenandoahLock.hpp
index 7c91df191e5..5041419b2c7 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahLock.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahLock.hpp
@@ -38,15 +38,19 @@ private:
   shenandoah_padding(0);
   Atomic<LockState> _state;
   shenandoah_padding(1);
+#ifdef ASSERT
   Atomic<Thread*> _owner;
   shenandoah_padding(2);
+#endif
 
   template<bool ALLOW_BLOCK>
   void contended_lock_internal(JavaThread* java_thread);
   static void yield_or_sleep(int &yields);
 
 public:
-  ShenandoahLock() : _state(unlocked), _owner(nullptr) {};
+  ShenandoahLock() : _state(unlocked) {
+    DEBUG_ONLY(_owner.store_relaxed(nullptr);)
+  };
 
   void lock(bool allow_block_for_safepoint = false) {
     assert(_owner.load_relaxed() != Thread::current(), "reentrant locking attempt, would deadlock");