diff --git a/gc.c b/gc.c
index 4976525d..aa29a9a9 100644
--- a/gc.c
+++ b/gc.c
@@ -709,6 +709,12 @@ void gc_collector()
   //trace : 
   gc_collector_trace();
   gc_stage = STAGE_SWEEPING;
+
+TODO: before updating sweep to make it work w/new GC, need to
+update the heap functions to be thread safe. ideally want to
+try to minimize amount of locking - IE, lock on individual ops
+IF POSSIBLE, instead of whole operations like 'alloc' and 'sweep'.
+  //
   //sweep : 
   // TODO: For each object x in the heap:
   // TODO:   if (color(x) = clearColor)