diff --git a/runtime/gc.c b/runtime/gc.c
index 0fd3b6443..b8d5d0540 100644
--- a/runtime/gc.c
+++ b/runtime/gc.c
@@ -1,5 +1,7 @@
 #define _GNU_SOURCE 1
 
+// #define DEBUG_PRINT
+
 #include "gc.h"
 
 #include "runtime_common.h"
@@ -65,8 +67,10 @@ void *alloc (size_t size) {
     // not enough place in the heap, need to perform GC cycle
      p = gc_alloc(size);
   }
+#ifdef DEBUG_PRINT
   printf("Object allocated: content [%p, %p) padding [%p, %p)\n", p, p + obj_size, p + obj_size, p + size * sizeof(size_t));
   fflush(stdout);
+#endif
   return p;
 }
 
@@ -188,7 +192,9 @@ void *gc_alloc_on_existing_heap (size_t size) {
 }
 
 void *gc_alloc (size_t size) {
+#ifdef DEBUG_PRINT
   printf("Reallocation!\n");
+#endif
   fflush(stdout);
 #if defined(DEBUG_VERSION) && defined(DEBUG_PRINT)
   fprintf(stderr, "===============================GC cycle has started\n");
@@ -271,9 +277,7 @@ void compact_phase (size_t additional_size) {
   size_t next_heap_pseudo_size = MAX(next_heap_size, heap.size);
 
   memory_chunk old_heap = heap;
-  heap.begin            = NULL;
-  // mremap(
-  //     heap.begin, WORDS_TO_BYTES(heap.size), WORDS_TO_BYTES(next_heap_pseudo_size), MREMAP_MAYMOVE);
+  heap.begin            = mremap(heap.begin, WORDS_TO_BYTES(heap.size), WORDS_TO_BYTES(next_heap_pseudo_size), MREMAP_MAYMOVE);
   if (heap.begin == MAP_FAILED) {
     perror("ERROR: compact_phase: mremap failed\n");
     exit(1);
@@ -885,7 +889,9 @@ void *alloc_string (auint len) {
   obj->id = cur_id;
 #endif
   obj->forward_address = 0;
+#ifdef DEBUG_PRINT
   printf("Allocated string\n");
+#endif
   return obj;
 }
 
@@ -899,7 +905,9 @@ void *alloc_array (auint len) {
   obj->id = cur_id;
 #endif
   obj->forward_address = 0;
+#ifdef DEBUG_PRINT
   printf("Allocated array\n");
+#endif
   return obj;
 }
 
@@ -914,7 +922,9 @@ void *alloc_sexp (auint members) {
 #endif
   obj->forward_address = 0;
   obj->tag             = 0;
+#ifdef DEBUG_PRINT
   printf("Allocated sexp\n");
+#endif
   return obj;
 }
 
@@ -929,6 +939,8 @@ void *alloc_closure (auint captured) {
   obj->id = cur_id;
 #endif
   obj->forward_address = 0;
+#ifdef DEBUG_PRINT
   printf("Allocated closure\n");
+#endif
   return obj;
 }
diff --git a/runtime/gc.h b/runtime/gc.h
index 9e562976e..b9eb0d12e 100644
--- a/runtime/gc.h
+++ b/runtime/gc.h
@@ -43,7 +43,7 @@
 // #  define MINIMUM_HEAP_CAPACITY (1 << 2)
 //#define MINIMUM_HEAP_CAPACITY (1 << 30)
 //#define MINIMUM_HEAP_CAPACITY (30)
-#define MINIMUM_HEAP_CAPACITY (30)
+#define MINIMUM_HEAP_CAPACITY (100)
 // #endif
 
 #include <stdbool.h>
diff --git a/runtime/runtime_common.h b/runtime/runtime_common.h
index 1d55ff707..cdeb70f09 100644
--- a/runtime/runtime_common.h
+++ b/runtime/runtime_common.h
@@ -38,9 +38,9 @@ auint;  // adaptive unsigned int
 #define CLOSURE_TAG 0x00000007
 #define UNBOXED_TAG 0x00000009   // Not actually a data_header; used to return from LkindOf
 #ifdef X86_64
-#define LEN_MASK (UINT64_MAX-7)
+#define LEN_MASK (UINT64_MAX^7)
 #else
-#define LEN_MASK (UINT32_MAX-7)
+#define LEN_MASK (UINT32_MAX^7)
 #endif
 #define LEN(x) (ptrt)(((ptrt)x & LEN_MASK) >> 3)
 #define TAG(x) (x & 7)