--- old/src/share/vm/gc/g1/g1MarkSweep.cpp	2017-04-25 16:44:37.479175106 +0200
+++ new/src/share/vm/gc/g1/g1MarkSweep.cpp	2017-04-25 16:44:37.335175111 +0200
@@ -333,7 +333,7 @@
   hr->prepare_for_compaction(cp);
   // Also clear the part of the card table that will be unused after
   // compaction.
-  _mrbs->clear(MemRegion(hr->compaction_top(), end));
+  _ct->clear(MemRegion(hr->compaction_top(), end));
 }
 
 void G1PrepareCompactClosure::update_sets() {