diff --git a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp
index b7b3da6..1a915aa 100644
--- a/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp
+++ b/hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp
@@ -994,6 +994,8 @@ size_t CompactibleFreeListSpace::block_size(const HeapWord* p) const {
         return res;
       }
     } else {
+      OrderAccess::acquire();
+
       // Ensure klass read before size.
       Klass* k = oop(p)->klass_or_null_acquire();
       if (k != NULL) {
@@ -1044,6 +1046,8 @@ const {
         return res;
       }
     } else {
+      OrderAccess::acquire();
+
       // Ensure klass read before size.
       Klass* k = oop(p)->klass_or_null_acquire();
       if (k != NULL) {
@@ -1098,6 +1102,9 @@ bool CompactibleFreeListSpace::block_is_obj(const HeapWord* p) const {
   // assert(CollectedHeap::use_parallel_gc_threads() || _bt.block_start(p) == p,
   //        "Should be a block boundary");
   if (FreeChunk::indicatesFreeChunk(p)) return false;
+
+  OrderAccess::acquire();
+
   Klass* k = oop(p)->klass_or_null_acquire();
   if (k != NULL) {
     // Ignore mark word because it may have been used to