diff --git a/gc.c b/gc.c
index fd657823..d11a33d4 100644
--- a/gc.c
+++ b/gc.c
@@ -161,7 +161,7 @@ size_t gc_heap_total_size(gc_heap *h)
 
 void gc_mark(gc_heap *h, object obj)
 {
-  if (!obj || is_marked(obj))
+  if (nullp(obj) || is_value_type(obj) || mark(obj))
     return;
 
 #if GC_DEBUG_PRINTFS
@@ -232,7 +232,7 @@ size_t gc_sweep(gc_heap *h, size_t *sum_freed_ptr)
       // END DEBUG
 #endif
 
-      if (!is_marked(p)) {
+      if (!mark(p)) {
 #if GC_DEBUG_PRINTFS
         fprintf(stdout, "sweep: object is not marked %p\n", p);
 #endif
diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index f773535a..841ce5a0 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -51,7 +51,6 @@ struct gc_header_type_t {
   unsigned int mark; // mark bits (only need 2)
   // TODO: forwarding address (probably not needed for mark/sweep), anything else???
 };
-#define is_marked(x) (is_object_type(x) && ((list)x)->hdr.mark)
 #define mark(x) (((list) x)->hdr.mark)
 
 /* HEAP definitions */
@@ -76,13 +75,13 @@ gc_heap *gc_heap_last(gc_heap *h);
 size_t gc_heap_total_size(gc_heap *h);
 void gc_mark(gc_heap *h, object obj);
 size_t gc_sweep(gc_heap *h, size_t *sum_freed_ptr);
-void gc_collect(gc_heap *h, size_t *sum_freed);
+size_t gc_collect(gc_heap *h, size_t *sum_freed);
 void gc_thr_grow_move_buffer(gc_thread_data *d);
 void gc_thr_add_to_move_buffer(gc_thread_data *d, int *alloci, object obj);
 
 /* GC debugging flags */
 //#define DEBUG_GC 0
-#define GC_DEBUG_PRINTFS 0
+#define GC_DEBUG_PRINTFS 1
 
 /* Show diagnostic information for the GC when program terminates */
 #define DEBUG_SHOW_DIAG 0
diff --git a/runtime.c b/runtime.c
index 04060d72..dac32078 100644
--- a/runtime.c
+++ b/runtime.c
@@ -2353,7 +2353,7 @@ void Cyc_apply_from_buf(int argc, object prim, object *buf) {
 // if the heap was expanded during alloc, and after all the allocs are done
 // after a minor GC (or during the minor GC), call into this function to
 // free up unused space
-void gc_collect(gc_heap *h, size_t *sum_freed) 
+size_t gc_collect(gc_heap *h, size_t *sum_freed) 
 {
   printf("(heap: %p size: %d)\n", h, (unsigned int)gc_heap_total_size(h));
   // Mark global variables
@@ -2369,7 +2369,7 @@ void gc_collect(gc_heap *h, size_t *sum_freed)
   // conservative mark?
   // weak refs?
   // finalize?
-  gc_sweep(h, sum_freed);
+  return gc_sweep(h, sum_freed);
   // debug print free stats
   // return value from sweep??
 }
@@ -2594,7 +2594,7 @@ void GC(cont, args, num_args) closure cont; object *args; int num_args;
   int scani = 0, alloci = 0; // TODO: not quite sure how to do this yet, want to user pointers but realloc can move them... need to think about how this will work
   int heap_grown = 0;
 
-fprintf(stdout, "DEBUG, started minor GC\n"); // JAE DEBUG
+//fprintf(stdout, "DEBUG, started minor GC\n"); // JAE DEBUG
   // Prevent overrunning buffer
   if (num_args > NUM_GC_ANS) {
     printf("Fatal error - too many arguments (%d) to GC\n", num_args);
@@ -2707,16 +2707,18 @@ fprintf(stdout, "DEBUG, started minor GC\n"); // JAE DEBUG
 
   // Check if we need to do a major GC
   if (heap_grown) {
-    size_t freed = 0;
+    size_t freed = 0, max_freed = 0;
 fprintf(stdout, "DEBUG, starting major mark/sweep GC\n"); // JAE DEBUG
     gc_mark(Cyc_heap, cont);
     for (i = 0; i < num_args; i++){ 
       gc_mark(Cyc_heap, args[i]);
     }
-    gc_collect(Cyc_heap, &freed);
+    max_freed = gc_collect(Cyc_heap, &freed);
+printf("done, freed = %d, max_freed = %d\n", freed, max_freed);
+exit(1); // JAE DEBUG
   }
 
-fprintf(stdout, "DEBUG, finished minor GC\n"); // JAE DEBUG
+//fprintf(stdout, "DEBUG, finished minor GC\n"); // JAE DEBUG
   longjmp(jmp_main,1); // Return globals gc_cont, gc_ans
 }