diff --git a/include/alisp/lisp.h b/include/alisp/lisp.h
index 21b8ddf..3979b2a 100644
--- a/include/alisp/lisp.h
+++ b/include/alisp/lisp.h
@@ -71,6 +71,12 @@ typedef struct
 {
   vec_t conses;
   vec_t vectors;
+  u64 num_conses, num_vectors;
+} sys_mem_t;
+
+typedef struct
+{
+  sys_mem_t memory;
   sym_table_t symtable;
 } sys_t;
 
diff --git a/src/lisp.c b/src/lisp.c
index 3d1b475..12ee334 100644
--- a/src/lisp.c
+++ b/src/lisp.c
@@ -23,21 +23,22 @@ lisp_t *sys_alloc(sys_t *sys, tag_t type)
   {
     cons_t *cons = calloc(1, sizeof(*cons));
     lisp_t *lisp = tag_cons(cons);
-    vec_append(&sys->conses, &lisp, sizeof(&lisp));
+    vec_append(&sys->memory.conses, &lisp, sizeof(&lisp));
+    sys->memory.num_conses++;
     return lisp;
   }
   case TAG_VEC:
   {
     vec_t *vec   = calloc(1, sizeof(*vec));
     lisp_t *lisp = tag_vec(vec);
-    vec_append(&sys->vectors, &lisp, sizeof(&lisp));
+    vec_append(&sys->memory.vectors, &lisp, sizeof(&lisp));
+    sys->memory.num_vectors++;
     return lisp;
   }
   // Shouldn't be registered
   case TAG_NIL:
   case TAG_INT:
   case TAG_SYM:
-  case NUM_TAGS:
   default:
     FAIL("Unreachable");
   }
@@ -47,12 +48,13 @@ lisp_t *sys_alloc(sys_t *sys, tag_t type)
 u64 sys_cost(sys_t *sys)
 {
   u64 vec_capacity = 0;
-  for (u64 i = 0; i < VEC_SIZE(&sys->vectors, lisp_t *); ++i)
+  for (u64 i = 0; i < sys->memory.num_vectors; ++i)
   {
-    lisp_t *vec = VEC_GET(&sys->vectors, i, lisp_t *);
+    lisp_t *vec = VEC_GET(&sys->memory.vectors, i, lisp_t *);
     vec_capacity += as_vec(vec)->capacity;
   }
-  return sym_table_cost(&sys->symtable) + sys->conses.capacity + vec_capacity;
+  return sym_table_cost(&sys->symtable) +
+         (sys->memory.num_conses * sizeof(cons_t)) + vec_capacity;
 }
 
 void sys_free(sys_t *sys)
@@ -60,22 +62,22 @@ void sys_free(sys_t *sys)
   sym_table_free(&sys->symtable);
 
   // Iterate through each cell of memory currently allocated and free them
-  for (size_t i = 0; i < VEC_SIZE(&sys->conses, lisp_t **); ++i)
+  for (size_t i = 0; i < VEC_SIZE(&sys->memory.conses, lisp_t **); ++i)
   {
-    lisp_t *allocated = VEC_GET(&sys->conses, i, lisp_t *);
+    lisp_t *allocated = VEC_GET(&sys->memory.conses, i, lisp_t *);
     lisp_free(allocated);
   }
 
   // Iterate through each cell of memory currently allocated and free them
-  for (size_t i = 0; i < VEC_SIZE(&sys->vectors, lisp_t **); ++i)
+  for (size_t i = 0; i < VEC_SIZE(&sys->memory.vectors, lisp_t **); ++i)
   {
-    lisp_t *allocated = VEC_GET(&sys->vectors, i, lisp_t *);
+    lisp_t *allocated = VEC_GET(&sys->memory.vectors, i, lisp_t *);
     lisp_free(allocated);
   }
 
   // Free the containers
-  vec_free(&sys->conses);
-  vec_free(&sys->vectors);
+  vec_free(&sys->memory.conses);
+  vec_free(&sys->memory.vectors);
 
   // Ensure no one treats this as active in any sense
   memset(sys, 0, sizeof(*sys));