diff --git a/vm/data_gc.cpp b/vm/data_gc.cpp
index ac0402b47d..408a70ea5e 100755
--- a/vm/data_gc.cpp
+++ b/vm/data_gc.cpp
@@ -3,36 +3,6 @@
 namespace factor
 {
 
-/* used during garbage collection only */
-zone *newspace;
-bool performing_gc;
-bool performing_compaction;
-cell collecting_gen;
-
-/* if true, we are collecting aging space for the second time, so if it is still
-full, we go on to collect tenured */
-bool collecting_aging_again;
-
-/* in case a generation fills up in the middle of a gc, we jump back
-up to try collecting the next generation. */
-jmp_buf gc_jmp;
-
-gc_stats stats[max_gen_count];
-u64 cards_scanned;
-u64 decks_scanned;
-u64 card_scan_time;
-cell code_heap_scans;
-
-/* What generation was being collected when copy_code_heap_roots() was last
-called? Until the next call to add_code_block(), future
-collections of younger generations don't have to touch the code
-heap. */
-cell last_code_heap_scan;
-
-/* sometimes we grow the heap */
-bool growing_data_heap;
-data_heap *old_data_heap;
-
 void factorvm::init_data_gc()
 {
 	performing_gc = false;
diff --git a/vm/data_gc.hpp b/vm/data_gc.hpp
index 47d2657587..68b2b4a936 100755
--- a/vm/data_gc.hpp
+++ b/vm/data_gc.hpp
@@ -10,14 +10,6 @@ struct gc_stats {
 	u64 bytes_copied;
 };
 
-extern zone *newspace;
-
-extern bool performing_compaction;
-extern cell collecting_gen;
-extern bool collecting_aging_again;
-
-extern cell last_code_heap_scan;
-
 void init_data_gc();
 
 void gc();
@@ -41,8 +33,6 @@ void clear_gc_stats();
 PRIMITIVE(clear_gc_stats);
 PRIMITIVE(become);
 
-extern bool growing_data_heap;
-
 
 VM_ASM_API void inline_gc(cell *gc_roots_base, cell gc_roots_size);
 
diff --git a/vm/vm.hpp b/vm/vm.hpp
index a58ac1ad9e..59d9d277f8 100644
--- a/vm/vm.hpp
+++ b/vm/vm.hpp
@@ -170,6 +170,36 @@ struct factorvm {
 
 
 	//data_gc
+	/* used during garbage collection only */
+	zone *newspace;
+	bool performing_gc;
+	bool performing_compaction;
+	cell collecting_gen;
+
+	/* if true, we collecting aging space for the second time, so if it is still
+	   full, we go on to collect tenured */
+	bool collecting_aging_again;
+
+	/* in case a generation fills up in the middle of a gc, we jump back
+	   up to try collecting the next generation. */
+	jmp_buf gc_jmp;
+
+	gc_stats stats[max_gen_count];
+	u64 cards_scanned;
+	u64 decks_scanned;
+	u64 card_scan_time;
+	cell code_heap_scans;
+
+	/* What generation was being collected when copy_code_heap_roots() was last
+	   called? Until the next call to add_code_block(), future
+	   collections of younger generations don't have to touch the code
+	   heap. */
+	cell last_code_heap_scan;
+
+	/* sometimes we grow the heap */
+	bool growing_data_heap;
+	data_heap *old_data_heap;
+
 	void init_data_gc();
 	object *copy_untagged_object_impl(object *pointer, cell size);
 	object *copy_object_impl(object *untagged);