diff -r f51af0093d29 -r a737bbd385f5 hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.cpp
--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.cpp	Tue Jul 17 11:52:10 2012 -0700
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegionSet.cpp	Tue Jul 17 14:57:02 2012 -0700
@@ -292,7 +292,7 @@
     assert(length() >  0 && _tail != NULL, hrs_ext_msg(this, "invariant"));
     from_list->_tail->set_next(_head);
   } else {
-    assert(length() == 0 && _head == NULL, hrs_ext_msg(this, "invariant"));
+    assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant"));
     _tail = from_list->_tail;
   }
   _head = from_list->_head;