--- old/src/share/vm/gc/g1/g1ConcurrentMark.cpp	2016-02-11 13:39:13.293819894 -0500
+++ new/src/share/vm/gc/g1/g1ConcurrentMark.cpp	2016-02-11 13:39:12.581779520 -0500
@@ -2271,7 +2271,7 @@
   SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
   guarantee(has_overflown() ||
             satb_mq_set.completed_buffers_num() == 0,
-            "Invariant: has_overflown = %s, num buffers = %d",
+            "Invariant: has_overflown = %s, num buffers = " SIZE_FORMAT,
             BOOL_TO_STR(has_overflown()),
             satb_mq_set.completed_buffers_num());