diff --git a/src/gc/mark_sweep.h b/src/gc/mark_sweep.h
index dc722a0..11ce32f 100644
--- a/src/gc/mark_sweep.h
+++ b/src/gc/mark_sweep.h
@@ -423,10 +423,12 @@
   UniquePtr<Barrier> gc_barrier_;
   Mutex large_object_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
   Mutex mark_stack_expand_lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
+
+  const bool is_concurrent_;
+
   TimingLogger timings_;
   CumulativeLogger cumulative_timings_;
 
-  bool is_concurrent_;
   bool clear_soft_references_;
 
   friend class AddIfReachesAllocSpaceVisitor; // Used by mod-union table.