diff --git a/gc.c b/gc.c
index a88d1af0..37752593 100644
--- a/gc.c
+++ b/gc.c
@@ -17,7 +17,7 @@ gc_heap *gc_heap_create(size_t size, size_t max_size, size_t chunk_size)
   gc_free_list *free, *next;
   gc_heap *h;
   // TODO: mmap?
-  h = malloc(size);
+  h = malloc(gc_heap_pad_size(size));
   if (!h) return NULL;
   h->size = size;
   h->chunk_size = chunk_size;
@@ -32,6 +32,14 @@ printf("DEBUG h->data addr: %p\n", h->data);
   free->next = next;
   next->size = size - gc_heap_align(gc_free_chunk_size);
   next->next = NULL;
+//#if GC_DEBUG_PRINTFS
+  fprintf(stderr, ("heap: %p-%p data: %p-%p"),
+          h, ((char*)h)+sexp_heap_pad_size(size), h->data, h->data + size);
+  fprintf(stderr, ("first: %p end: %p"),
+          (object)sexp_heap_first_block(h), (object)sexp_heap_end(h));
+  fprintf(stderr, ("free1: %p-%p free2: %p-%p"),
+          free, ((char*)free)+free->size, next, ((char*)next)+next->size);
+//#endif
   return h;
 }
 
@@ -101,9 +109,9 @@ void *gc_alloc(gc_heap *h, size_t size, int *heap_grown)
       exit(1); // TODO: throw error???
     }
   }
-#if GC_DEBUG_PRINTFS
-//  fprintf(stdout, "alloc %p\n", result);
-#endif
+//#if GC_DEBUG_PRINTFS
+  fprintf(stdout, "alloc %p size = %d\n", result, size);
+//#endif
   return result;
 }
 
diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index 841ce5a0..d8fc47d1 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -58,6 +58,7 @@ struct gc_header_type_t {
 #define gc_heap_first_block(h) ((object)(h->data + gc_heap_align(gc_free_chunk_size)))
 #define gc_heap_last_block(h) ((object)((char*)h->data + h->size - gc_heap_align(gc_free_chunk_size)))
 #define gc_heap_end(h) ((object)((char*)h->data + h->size))
+#define gc_heap_pad_size(s) (sizeof(struct gc_heap_t) + (s) + gc_heap_align(1))
 #define gc_free_chunk_size (sizeof(gc_free_list))
 
 #define gc_align(n, bits) (((n)+(1<<(bits))-1)&(((unsigned int)-1)-((1<<(bits))-1)))
diff --git a/runtime.c b/runtime.c
index 41e89435..34429855 100644
--- a/runtime.c
+++ b/runtime.c
@@ -2716,7 +2716,7 @@ fprintf(stdout, "DEBUG, starting major mark/sweep GC\n"); // JAE DEBUG
     }
     max_freed = gc_collect(Cyc_heap, &freed);
 printf("done, freed = %d, max_freed = %d\n", freed, max_freed);
-//exit(1); // JAE DEBUG
+exit(1); // JAE DEBUG
   }
 
 //fprintf(stdout, "DEBUG, finished minor GC\n"); // JAE DEBUG