diff --git a/vm/data_heap.cpp b/vm/data_heap.cpp
index 020954bf05..e484a18b7a 100755
--- a/vm/data_heap.cpp
+++ b/vm/data_heap.cpp
@@ -237,7 +237,7 @@ void init_data_heap(cell gens,cell young_size,cell aging_size,cell tenured_size,
 }
 
 /* Size of the object pointed to by a tagged pointer */
-cell object_size(cell tagged)
+cell factorvm::object_size(cell tagged)
 {
 	if(immediate_p(tagged))
 		return 0;
@@ -245,6 +245,11 @@ cell object_size(cell tagged)
 		return untagged_object_size(untag<object>(tagged));
 }
 
+cell object_size(cell tagged)
+{
+	return vm->object_size(tagged);
+}
+
 /* Size of the object pointed to by an untagged pointer */
 cell factorvm::untagged_object_size(object *pointer)
 {
diff --git a/vm/vm.hpp b/vm/vm.hpp
index 1ed6d965bc..3aab1061ff 100644
--- a/vm/vm.hpp
+++ b/vm/vm.hpp
@@ -154,6 +154,9 @@ struct factorvm {
 	inline void vmprim_end_scan();
 	template<typename T> void each_object(T &functor);
 	cell find_all_words();
+	cell object_size(cell tagged);
+	// next method here:
+
 	
 	//write barrier
 	inline card *addr_to_card(cell a);
@@ -412,7 +415,6 @@ struct factorvm {
 	inline double fixnum_to_float(cell tagged);
 	template <typename T> T *untag_check(cell value);
 	template <typename T> T *untag(cell value);
-	// next method here:
 	
 	//io
 	void init_c_io();