--- old/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp	2018-02-02 01:04:42.977309395 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp	2018-02-02 01:04:42.553314911 +0100
@@ -1832,6 +1832,7 @@
 
 bool ShenandoahForwardedIsAliveClosure::do_object_b(oop obj) {
   assert(_heap != NULL, "sanity");
+  if (oopDesc::is_null(obj)) return true;
   assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static_not_null(obj)) ||
          (!_heap->is_marked_next(obj)), "from-space obj must not be marked");
 
@@ -1851,6 +1852,7 @@
 
 bool ShenandoahIsAliveClosure::do_object_b(oop obj) {
   assert(_heap != NULL, "sanity");
+  if (oopDesc::is_null(obj)) return true;
   assert(!oopDesc::is_null(obj), "null");
   assert(oopDesc::unsafe_equals(obj, ShenandoahBarrierSet::resolve_oop_static_not_null(obj)), "only query to-space");
   return _heap->is_marked_next(obj);