diff a/src/hotspot/share/gc/g1/g1HeapVerifier.cpp b/src/hotspot/share/gc/g1/g1HeapVerifier.cpp
--- a/src/hotspot/share/gc/g1/g1HeapVerifier.cpp
+++ b/src/hotspot/share/gc/g1/g1HeapVerifier.cpp
@@ -66,11 +66,11 @@
     T heap_oop = RawAccess<>::oop_load(p);
     if (!CompressedOops::is_null(heap_oop)) {
       oop obj = CompressedOops::decode_not_null(heap_oop);
       if (_g1h->is_obj_dead_cond(obj, _vo)) {
         Log(gc, verify) log;
-        log.error("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT, p2i(p), p2i(obj));
+        log.error("Root location " PTR_FORMAT " points to dead obj " PTR_FORMAT " vo %d", p2i(p), p2i(obj), _vo);
         ResourceMark rm;
         LogStream ls(log.error());
         obj->print_on(&ls);
         _failures = true;
       }
@@ -181,21 +181,30 @@
 };
 
 class VerifyLivenessOopClosure: public BasicOopIterateClosure {
   G1CollectedHeap* _g1h;
   VerifyOption _vo;
+  oop _o;
 public:
-  VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
-    _g1h(g1h), _vo(vo)
+  VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo, oop o):
+    _g1h(g1h), _vo(vo), _o(o)
   { }
   void do_oop(narrowOop *p) { do_oop_work(p); }
   void do_oop(      oop *p) { do_oop_work(p); }
 
   template <class T> void do_oop_work(T *p) {
     oop obj = RawAccess<>::oop_load(p);
     guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
-              "Dead object referenced by a not dead object");
+              "vo %d Dead object " PTR_FORMAT " (%s) referenced by a not dead object " PTR_FORMAT " (%s) _g1h->is_obj_dead_cond(obj, _vo) %d marked %d since prev mark %d since next mark %d",
+            _vo,
+              p2i(obj), _g1h->heap_region_containing(obj)->get_short_type_str(),
+              p2i(_o), _g1h->heap_region_containing(_o)->get_short_type_str(),
+            _g1h->is_obj_dead_cond(obj, _vo),
+            _g1h->concurrent_mark()->prev_mark_bitmap()->is_marked(_o),
+            _g1h->heap_region_containing(_o)->obj_allocated_since_prev_marking(_o),
+            _g1h->heap_region_containing(_o)->obj_allocated_since_next_marking(_o)
+            );
   }
 };
 
 class VerifyObjsInRegionClosure: public ObjectClosure {
 private:
@@ -210,11 +219,11 @@
   VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
     : _live_bytes(0), _hr(hr), _vo(vo) {
     _g1h = G1CollectedHeap::heap();
   }
   void do_object(oop o) {
-    VerifyLivenessOopClosure isLive(_g1h, _vo);
+    VerifyLivenessOopClosure isLive(_g1h, _vo, o);
     assert(o != NULL, "Huh?");
     if (!_g1h->is_obj_dead_cond(o, _vo)) {
       // If the object is alive according to the full gc mark,
       // then verify that the marking information agrees.
       // Note we can't verify the contra-positive of the