diff --git a/gc.c b/gc.c
index 852effb0..793ab4a8 100644
--- a/gc.c
+++ b/gc.c
@@ -850,7 +850,7 @@ void gc_mut_update(gc_thread_data *thd, object old_obj, object value)
 }
 
 // TODO: still need to handle case where a mutator is blocked
-void gc_mut_cooperate(gc_thread_data *thd)
+void gc_mut_cooperate(gc_thread_data *thd, int buf_len)
 {
   int i, status = ATOMIC_GET(&gc_status_col);
   if (thd->gc_status != status) {
@@ -863,18 +863,23 @@ void gc_mut_cooperate(gc_thread_data *thd)
     }
     else if (thd->gc_status == STATUS_SYNC2) {
       // Mark thread "roots"
-      // TODO: below is efficient, but is there a chance we are missing anything by
-      // doing this instead of marking the objects in moveBuf??
+      // In this case, mark everything the collector moved to the heap
+      for (i = 0; i < buf_len; i++) {
+        gc_mark_gray(thd, thd->moveBuf[i]);
 #if GC_DEBUG_VERBOSE
-fprintf(stderr, "gc_cont %p\n", thd->gc_cont);
+        fprintf(stderr, "mark from move buf %i %p\n", i, thd->moveBuf[i]);
 #endif
-      gc_mark_gray(thd, thd->gc_cont);
-      for (i = 0; i < thd->gc_num_args; i++) {
-#if GC_DEBUG_VERBOSE
-fprintf(stderr, "gc_args[%d] %p\n", i, thd->gc_args[i]);
-#endif
-        gc_mark_gray(thd, thd->gc_args[i]);
       }
+//#if GC_DEBUG_VERBOSE
+//fprintf(stderr, "gc_cont %p\n", thd->gc_cont);
+//#endif
+//      gc_mark_gray(thd, thd->gc_cont);
+//      for (i = 0; i < thd->gc_num_args; i++) {
+//#if GC_DEBUG_VERBOSE
+//fprintf(stderr, "gc_args[%d] %p\n", i, thd->gc_args[i]);
+//#endif
+//        gc_mark_gray(thd, thd->gc_args[i]);
+//      }
       thd->gc_alloc_color = ATOMIC_GET(&gc_color_mark);
     }
     thd->gc_status = status;
diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index ea28aadd..7b74f290 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -159,7 +159,7 @@ void gc_thread_data_init(gc_thread_data *thd, int mut_num, char *stack_base, lon
 void gc_thread_data_free(gc_thread_data *thd);
 // Prototypes for mutator/collector:
 void gc_mut_update(gc_thread_data *thd, object old_obj, object value);
-void gc_mut_cooperate(gc_thread_data *thd);
+void gc_mut_cooperate(gc_thread_data *thd, int buf_len);
 void gc_stack_mark_refs_gray(gc_thread_data *thd, object obj, int depth);
 void gc_stack_mark_gray(gc_thread_data *thd, object obj);
 void gc_mark_gray(gc_thread_data *thd, object obj);
diff --git a/runtime.c b/runtime.c
index e3826ab5..11ad7906 100644
--- a/runtime.c
+++ b/runtime.c
@@ -2582,7 +2582,7 @@ void GC(void *data, closure cont, object *args, int num_args)
   object low_limit = &tmp; // This is one end of the stack...
   object high_limit = ((gc_thread_data *)data)->stack_start;
   int i;
-  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 scani = 0, alloci = 0;
   int heap_grown = 0;
 
 //fprintf(stdout, "DEBUG, started minor GC\n"); // JAE DEBUG
@@ -2697,7 +2697,7 @@ void GC(void *data, closure cont, object *args, int num_args)
   }
 
   // Cooperate with the collector thread
-  gc_mut_cooperate((gc_thread_data *)data);
+  gc_mut_cooperate((gc_thread_data *)data, alloci);
 
 #if GC_DEBUG_TRACE
   fprintf(stderr, "done with minor GC\n");