diff a/src/hotspot/share/gc/shenandoah/shenandoahThreadLocalData.cpp b/src/hotspot/share/gc/shenandoah/shenandoahThreadLocalData.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahThreadLocalData.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahThreadLocalData.cpp
@@ -29,10 +29,11 @@
 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 #include "gc/shenandoah/shenandoahThreadLocalData.hpp"
 
 ShenandoahThreadLocalData::ShenandoahThreadLocalData() :
   _gc_state(0),
+  _gc_state_fast_array{},
   _satb_mark_queue(&ShenandoahBarrierSet::satb_mark_queue_set()),
   _card_table(nullptr),
   _gclab(nullptr),
   _gclab_size(0),
   _shenandoah_plab(nullptr),