diff --git a/include/cyclone/runtime.h b/include/cyclone/runtime.h
index e2f898b6..d7ec7d42 100644
--- a/include/cyclone/runtime.h
+++ b/include/cyclone/runtime.h
@@ -198,6 +198,7 @@ void Cyc_exit_thread(gc_thread_data *thd);
 object Cyc_thread_sleep(void *data, object timeout);
 void GC(void *,closure,object*,int);
 object Cyc_trigger_minor_gc(void *data, object cont);
+object copy2heap(void *data, object obj);
 
 void Cyc_st_add(void *data, char *frame);
 void Cyc_st_print(void *data, FILE *out);
diff --git a/runtime.c b/runtime.c
index b86c8712..6b6c4f44 100644
--- a/runtime.c
+++ b/runtime.c
@@ -2866,16 +2866,15 @@ object Cyc_thread_sleep(void *data, object timeout)
   return boolean_t;
 }
 
-// WIP for something to use to debug/use for threads
-//object copy2heap(void *data, object obj) 
-//{
-//  char stack_pos;
-//  gc_thread_data *thd = (gc_thread_data *)data;
-//  int on_stack = check_overflow(&stack_pos, obj) &&
-//                 check_overflow(obj, thd->stack_start);
-//  if (!is_object_type(obj) || !on_stack) {
-//    return obj;
-//  }
-//
-//  return gc_alloc(Cyc_heap, gc_allocated_bytes(obj, NULL, NULL), obj, data, &on_stack);
-//}
+object copy2heap(void *data, object obj) 
+{
+  char stack_pos;
+  gc_thread_data *thd = (gc_thread_data *)data;
+  int on_stack = check_overflow((object)(&stack_pos), obj) &&
+                 check_overflow(obj, (object)thd->stack_start);
+  if (!is_object_type(obj) || !on_stack) {
+    return obj;
+  }
+
+  return gc_alloc(Cyc_heap, gc_allocated_bytes(obj, NULL, NULL), obj, data, &on_stack);
+}
diff --git a/srfi/18.sld b/srfi/18.sld
index bb75fee2..8fd37b75 100644
--- a/srfi/18.sld
+++ b/srfi/18.sld
@@ -10,6 +10,7 @@
     thread-yield!
 ;    thread-terminate!
     ; For now, these are built-ins. No need for them here: make-mutex mutex-lock! mutex-unlock!
+    ->heap
   )
   (begin
     ;; Threading
@@ -45,4 +46,8 @@
     (define (thread-yield!) (thread-sleep! 1))
 ;    (define (thread-terminate!) (Cyc-end-thread!))
     ;; TODO: thread-join!
+    (define-c ->heap
+      "(void *data, int argc, closure _, object k, object obj)"
+      " object heap_obj = copy2heap(data, obj);
+        return_closcall1(data, k, heap_obj); ")
 ))