--- old/src/hotspot/share/gc/g1/dirtyCardQueue.hpp	2019-01-07 18:59:08.733995480 -0500
+++ new/src/hotspot/share/gc/g1/dirtyCardQueue.hpp	2019-01-07 18:59:08.485982459 -0500
@@ -28,8 +28,8 @@
 #include "gc/shared/ptrQueue.hpp"
 #include "memory/allocation.hpp"
 
-class FreeIdSet;
 class DirtyCardQueueSet;
+class G1FreeIdSet;
 class JavaThread;
 class Monitor;
 
@@ -103,8 +103,7 @@
 
   bool mut_process_buffer(BufferNode* node);
 
-  // Protected by the _cbl_mon.
-  FreeIdSet* _free_ids;
+  G1FreeIdSet* _free_ids;
 
   // The number of completed buffers processed by mutator and rs thread,
   // respectively.