--- old/src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp	2020-01-22 10:29:52.631852082 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahMarkCompact.cpp	2020-01-22 10:29:52.099843376 +0100
@@ -555,6 +555,7 @@
     T o = RawAccess<>::oop_load(p);
     if (!CompressedOops::is_null(o)) {
       oop obj = CompressedOops::decode_not_null(o);
+      assert_object_is_in_heap(p, obj);
       assert(_ctx->is_marked(obj), "must be marked");
       if (obj->is_forwarded()) {
         oop forw = obj->forwardee();