diff --git a/vm/callstack.cpp b/vm/callstack.cpp
index e4f03abca9..8df438206c 100755
--- a/vm/callstack.cpp
+++ b/vm/callstack.cpp
@@ -194,10 +194,10 @@ struct stack_frame_accumulator {
 
 	stack_frame_accumulator(factorvm *vm) : frames(vm) {} 
 
-	void operator()(stack_frame *frame)
+	void operator()(stack_frame *frame, factorvm *myvm)
 	{
-		gc_root<object> executing(frame_executing(frame),frames.elements.myvm);
-		gc_root<object> scan(frame_scan(frame),frames.elements.myvm);
+		gc_root<object> executing(frame_executing(frame),myvm);
+		gc_root<object> scan(frame_scan(frame),myvm);
 
 		frames.add(executing.value());
 		frames.add(scan.value());
diff --git a/vm/callstack.hpp b/vm/callstack.hpp
index ee097b528c..82fb93a1bc 100755
--- a/vm/callstack.hpp
+++ b/vm/callstack.hpp
@@ -22,16 +22,6 @@ PRIMITIVE(set_innermost_stack_frame_quot);
 
 VM_ASM_API void save_callstack_bottom(stack_frame *callstack_bottom);
 
-template<typename T> void iterate_callstack(cell top, cell bottom, T &iterator)
-{
-	stack_frame *frame = (stack_frame *)bottom - 1;
-
-	while((cell)frame >= top)
-	{
-		iterator(frame);
-		frame = frame_successor(frame);
-	}
-}
 
 
 }
diff --git a/vm/code_block.cpp b/vm/code_block.cpp
index 9486d7f3b3..b8d4621d38 100755
--- a/vm/code_block.cpp
+++ b/vm/code_block.cpp
@@ -137,9 +137,9 @@ void factorvm::undefined_symbol()
 	general_error(ERROR_UNDEFINED_SYMBOL,F,F,NULL);
 }
 
-void undefined_symbol()
+void undefined_symbol(factorvm *myvm)
 {
-	return vm->undefined_symbol();
+	return myvm->undefined_symbol();
 }
 
 /* Look up an external library symbol referenced by a compiled code block */
@@ -509,9 +509,9 @@ void factorvm::mark_stack_frame_step(stack_frame *frame)
 	mark_code_block(frame_code(frame));
 }
 
-void mark_stack_frame_step(stack_frame *frame)
+void mark_stack_frame_step(stack_frame *frame, factorvm *myvm)
 {
-	return vm->mark_stack_frame_step(frame);
+	return myvm->mark_stack_frame_step(frame);
 }
 
 /* Mark code blocks executing in currently active stack frames. */
diff --git a/vm/code_heap.cpp b/vm/code_heap.cpp
index 9399c9ae70..fb24af4044 100755
--- a/vm/code_heap.cpp
+++ b/vm/code_heap.cpp
@@ -176,9 +176,9 @@ void factorvm::forward_frame_xt(stack_frame *frame)
 	FRAME_RETURN_ADDRESS(frame) = (void *)((cell)forwarded + offset);
 }
 
-void forward_frame_xt(stack_frame *frame)
+void forward_frame_xt(stack_frame *frame,factorvm *myvm)
 {
-	return vm->forward_frame_xt(frame);
+	return myvm->forward_frame_xt(frame);
 }
 
 void factorvm::forward_object_xts()
diff --git a/vm/data_heap.hpp b/vm/data_heap.hpp
index 2bec35b8c1..67e3109924 100755
--- a/vm/data_heap.hpp
+++ b/vm/data_heap.hpp
@@ -98,23 +98,6 @@ PRIMITIVE(end_scan);
 
 cell find_all_words();
 
-/* Every object has a regular representation in the runtime, which makes GC
-much simpler. Every slot of the object until binary_payload_start is a pointer
-to some other object. */
-inline static void do_slots(cell obj, void (* iter)(cell *))
-{
-	cell scan = obj;
-	cell payload_start = binary_payload_start((object *)obj);
-	cell end = obj + payload_start;
-
-	scan += sizeof(cell);
-
-	while(scan < end)
-	{
-		iter((cell *)scan);
-		scan += sizeof(cell);
-	}
-}
 
 }
 
diff --git a/vm/debug.cpp b/vm/debug.cpp
index 5d033fd90e..eb64ad22d4 100755
--- a/vm/debug.cpp
+++ b/vm/debug.cpp
@@ -232,9 +232,9 @@ void factorvm::print_stack_frame(stack_frame *frame)
 	print_string("\n");
 }
 
-void print_stack_frame(stack_frame *frame)
+void print_stack_frame(stack_frame *frame, factorvm *myvm)
 {
-	return vm->print_stack_frame(frame);
+	return myvm->print_stack_frame(frame);
 }
 
 void factorvm::print_callstack()
@@ -356,9 +356,9 @@ void factorvm::find_data_references_step(cell *scan)
 	}
 }
 
-void find_data_references_step(cell *scan)
+void find_data_references_step(cell *scan,factorvm *myvm)
 {
-	return vm->find_data_references_step(scan);
+	return myvm->find_data_references_step(scan);
 }
 
 void factorvm::find_data_references(cell look_for_)
diff --git a/vm/image.cpp b/vm/image.cpp
index ee86dd5a3f..b8e89d5fcb 100755
--- a/vm/image.cpp
+++ b/vm/image.cpp
@@ -195,9 +195,9 @@ void factorvm::data_fixup(cell *cell)
 	*cell += (tenured->start - data_relocation_base);
 }
 
-void data_fixup(cell *cell)
+void data_fixup(cell *cell, factorvm *myvm)
 {
-	return vm->data_fixup(cell);
+	return myvm->data_fixup(cell);
 }
 
 template <typename TYPE> void factorvm::code_fixup(TYPE **handle)
@@ -258,9 +258,9 @@ void factorvm::fixup_stack_frame(stack_frame *frame)
 	code_fixup(&FRAME_RETURN_ADDRESS(frame));
 }
 
-void fixup_stack_frame(stack_frame *frame)
+void fixup_stack_frame(stack_frame *frame, factorvm *myvm)
 {
-	return vm->fixup_stack_frame(frame);
+	return myvm->fixup_stack_frame(frame);
 }
 
 void factorvm::fixup_callstack_object(callstack *stack)
diff --git a/vm/math.cpp b/vm/math.cpp
index 74caec3074..ed556f268a 100755
--- a/vm/math.cpp
+++ b/vm/math.cpp
@@ -367,7 +367,8 @@ unsigned int bignum_producer(unsigned int digit)
 inline void factorvm::vmprim_byte_array_to_bignum()
 {
 	cell n_digits = array_capacity(untag_check<byte_array>(dpeek()));
-	bignum * result = factor::digit_stream_to_bignum(n_digits,factor::bignum_producer,0x100,0);
+	//	bignum * result = factor::digit_stream_to_bignum(n_digits,factor::bignum_producer,0x100,0);
+	bignum * result = digit_stream_to_bignum(n_digits,factor::bignum_producer,0x100,0);
 	drepl(tag<bignum>(result));
 }
 
diff --git a/vm/vm.hpp b/vm/vm.hpp
index d0f31e4d3f..42a250832c 100644
--- a/vm/vm.hpp
+++ b/vm/vm.hpp
@@ -61,6 +61,8 @@ struct factorvm {
 	void type_error(cell type, cell tagged);
 	void general_error(vm_error_type error, cell arg1, cell arg2, stack_frame *callstack_top);
 
+	//callstack
+
 	// bignum
 	int bignum_equal_p(bignum * x, bignum * y);
 	enum bignum_comparison bignum_compare(bignum * x, bignum * y);
@@ -530,6 +532,10 @@ struct factorvm {
 	inline void vmprim_innermost_stack_frame_scan();
 	inline void vmprim_set_innermost_stack_frame_quot();
 	void save_callstack_bottom(stack_frame *callstack_bottom);
+	template<typename T> void iterate_callstack(cell top, cell bottom, T &iterator);
+	inline void do_slots(cell obj, void (* iter)(cell *,factorvm*));
+	// next method here:
+
 
 	//alien
 	char *pinned_alien_offset(cell obj);
@@ -1066,7 +1072,7 @@ template<typename TYPE> void factorvm::iterate_callstack_object(callstack *stack
 	{
 		stack_frame *frame = stack->frame_at(frame_offset);
 		frame_offset -= frame->size;
-		iterator(frame);
+		iterator(frame,this);
 	}
 }
 
@@ -1086,7 +1092,48 @@ inline cell tag_boolean(cell untagged)
 	return vm->tag_boolean(untagged);
 }
 
-// next method here:
+// callstack.hpp
+template<typename TYPE> void factorvm::iterate_callstack(cell top, cell bottom, TYPE &iterator)
+{
+	stack_frame *frame = (stack_frame *)bottom - 1;
+
+	while((cell)frame >= top)
+	{
+		iterator(frame,this);
+		frame = frame_successor(frame);
+	}
+}
+
+template<typename TYPE> void iterate_callstack(cell top, cell bottom, TYPE &iterator)
+{
+	return vm->iterate_callstack(top,bottom,iterator);
+}
+
+
+// data_heap.hpp
+/* Every object has a regular representation in the runtime, which makes GC
+much simpler. Every slot of the object until binary_payload_start is a pointer
+to some other object. */
+struct factorvm;
+inline void factorvm::do_slots(cell obj, void (* iter)(cell *,factorvm*))
+{
+	cell scan = obj;
+	cell payload_start = binary_payload_start((object *)obj);
+	cell end = obj + payload_start;
+
+	scan += sizeof(cell);
+
+	while(scan < end)
+	{
+		iter((cell *)scan,this);
+		scan += sizeof(cell);
+	}
+}
+
+inline void do_slots(cell obj, void (* iter)(cell *,factorvm*))
+{
+	return vm->do_slots(obj,iter);
+}
 
 
 }