diff --git a/src/hotspot/share/gc/g1/g1ParScanThreadState.cpp b/src/hotspot/share/gc/g1/g1ParScanThreadState.cpp
index f81e7ebec49..a3740982c45 100644
--- a/src/hotspot/share/gc/g1/g1ParScanThreadState.cpp
+++ b/src/hotspot/share/gc/g1/g1ParScanThreadState.cpp
@@ -83,7 +83,7 @@ G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h,
     _partial_objarray_chunk_size(ParGCArrayScanChunk),
     _partial_array_stepper(num_workers),
     _string_dedup_requests(),
-    _num_optional_regions(optional_cset_length),
+    _max_num_optional_regions(optional_cset_length),
     _numa(g1h->numa()),
     _obj_alloc_stat(NULL),
     EVAC_FAILURE_INJECTOR_ONLY(_evac_failure_inject_counter(0) COMMA)
@@ -106,7 +106,7 @@ G1ParScanThreadState::G1ParScanThreadState(G1CollectedHeap* g1h,
 
   _closures = G1EvacuationRootClosures::create_root_closures(this, _g1h);
 
-  _oops_into_optional_regions = new G1OopStarChunkedList[_num_optional_regions];
+  _oops_into_optional_regions = new G1OopStarChunkedList[_max_num_optional_regions];
 
   initialize_numa_stats();
 }
diff --git a/src/hotspot/share/gc/g1/g1ParScanThreadState.hpp b/src/hotspot/share/gc/g1/g1ParScanThreadState.hpp
index 6fb95ea6e93..cef6fe8c253 100644
--- a/src/hotspot/share/gc/g1/g1ParScanThreadState.hpp
+++ b/src/hotspot/share/gc/g1/g1ParScanThreadState.hpp
@@ -92,7 +92,8 @@ class G1ParScanThreadState : public CHeapObj<mtGC> {
 
   G1CardTable* ct() { return _ct; }
 
-  size_t _num_optional_regions;
+  // Maximum number of optional regions at start of gc.
+  size_t _max_num_optional_regions;
   G1OopStarChunkedList* _oops_into_optional_regions;
 
   G1NUMA* _numa;
diff --git a/src/hotspot/share/gc/g1/g1ParScanThreadState.inline.hpp b/src/hotspot/share/gc/g1/g1ParScanThreadState.inline.hpp
index c37f0f38e51..41553e6bf19 100644
--- a/src/hotspot/share/gc/g1/g1ParScanThreadState.inline.hpp
+++ b/src/hotspot/share/gc/g1/g1ParScanThreadState.inline.hpp
@@ -74,8 +74,8 @@ template <typename T>
 inline void G1ParScanThreadState::remember_root_into_optional_region(T* p) {
   oop o = RawAccess<IS_NOT_NULL>::oop_load(p);
   uint index = _g1h->heap_region_containing(o)->index_in_opt_cset();
-  assert(index < _num_optional_regions,
-         "Trying to access optional region idx %u beyond " SIZE_FORMAT, index, _num_optional_regions);
+  assert(index < _max_num_optional_regions,
+         "Trying to access optional region idx %u beyond " SIZE_FORMAT, index, _max_num_optional_regions);
   _oops_into_optional_regions[index].push_root(p);
 }
 
@@ -83,16 +83,16 @@ template <typename T>
 inline void G1ParScanThreadState::remember_reference_into_optional_region(T* p) {
   oop o = RawAccess<IS_NOT_NULL>::oop_load(p);
   uint index = _g1h->heap_region_containing(o)->index_in_opt_cset();
-  assert(index < _num_optional_regions,
-         "Trying to access optional region idx %u beyond " SIZE_FORMAT, index, _num_optional_regions);
+  assert(index < _max_num_optional_regions,
+         "Trying to access optional region idx %u beyond " SIZE_FORMAT, index, _max_num_optional_regions);
   _oops_into_optional_regions[index].push_oop(p);
   verify_task(p);
 }
 
 G1OopStarChunkedList* G1ParScanThreadState::oops_into_optional_region(const HeapRegion* hr) {
-  assert(hr->index_in_opt_cset() < _num_optional_regions,
+  assert(hr->index_in_opt_cset() < _max_num_optional_regions,
          "Trying to access optional region idx %u beyond " SIZE_FORMAT " " HR_FORMAT,
-         hr->index_in_opt_cset(), _num_optional_regions, HR_FORMAT_PARAMS(hr));
+         hr->index_in_opt_cset(), _max_num_optional_regions, HR_FORMAT_PARAMS(hr));
   return &_oops_into_optional_regions[hr->index_in_opt_cset()];
 }