--- old/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp	2015-02-17 09:29:37.040288877 +0100
+++ new/src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.cpp	2015-02-17 09:29:36.979287106 +0100
@@ -72,7 +72,7 @@
   _commit_size = commit_size;
 
   assert(_committed.size() == 0, "virtual space initialized more than once");
-  BitMap::idx_t size_in_commit_pages = round_to(rs.size(), commit_size);
+  BitMap::idx_t size_in_commit_pages = round_to(rs.size(), commit_size) / commit_size;
   _committed.resize(size_in_commit_pages, /* in_resource_area */ false);
   if (_special) {
     _dirty.resize(size_in_commit_pages, /* in_resource_area */ false);