diff --git a/scripts/repl.mes b/scripts/repl.mes
index ed8f256b..bd53889a 100755
--- a/scripts/repl.mes
+++ b/scripts/repl.mes
@@ -1,7 +1,6 @@
 #! /bin/sh
 # -*-scheme-*-
 MES=${MES-$(dirname $0)/mes}
-export MES_ARENA=${MES_ARENA-40000}
 prefix=module/
 cat $0 /dev/stdin | $MES $MES_FLAGS -- "$@"
 #paredit:|
diff --git a/src/gc.c b/src/gc.c
index 34e63c01..dcf9a507 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -24,21 +24,21 @@ SCM
 gc_up_arena () ///((internal))
 {
   ARENA_SIZE *= 2;
-  GC_SAFETY *= 2;
-#if _POSIX_SOURCE
   void *p = realloc (g_cells-1, 2*ARENA_SIZE*sizeof(struct scm));
-#else
-  char *p = g_cells;
-  p = realloc (p-sizeof (struct scm), 2*ARENA_SIZE*sizeof(struct scm));
-#endif
-
-#if _POSIX_SOURCE
   if (!p)
-    error (cell_symbol_system_error, cons (MAKE_STRING (cstring_to_list (strerror (errno))), MAKE_NUMBER (g_free)));
+    {
+      eputs ("realloc failed, g_free=");
+      eputs (itoa (g_free));
+      eputs (":");
+      eputs (itoa (ARENA_SIZE - g_free));
+      eputs ("\n");
+      assert (0);
+      exit (1);
+    }
   g_cells = (struct scm*)p;
   g_cells++;
-#endif
   gc_init_news ();
+
   return 0;
 }
 
@@ -132,12 +132,12 @@ SCM
 gc_check ()
 {
   if (g_free + GC_SAFETY > ARENA_SIZE)
-    gc_pop_frame (gc (gc_push_frame ()));
+    gc ();
   return cell_unspecified;
 }
 
 SCM
-gc ()
+gc_ () ///((internal))
 {
   if (g_debug == 2)
     eputs (".");
@@ -150,11 +150,30 @@ gc ()
       eputs ("]...");
     }
   g_free = 1;
-  if (g_cells < g_news && ARENA_SIZE < MAX_ARENA_SIZE)
-    gc_up_arena ();
+
+  if (g_cells < g_news
+      //&& g_free > ARENA_SIZE >> 2
+      && ARENA_SIZE < MAX_ARENA_SIZE)
+    {
+      if (g_debug == 2)
+        eputs ("+");
+      if (g_debug > 2)
+        {
+          eputs (" up[");
+          eputs (itoa (g_cells));
+          eputs (",");
+          eputs (itoa (g_news));
+          eputs (":");
+          eputs (itoa (ARENA_SIZE));
+          eputs (",");
+          eputs (itoa (MAX_ARENA_SIZE));
+          eputs ("]...");
+        }
+      gc_up_arena ();
+    }
+
   for (int i=g_free; i<g_symbol_max; i++)
     gc_copy (i);
-  make_tmps (g_news);
   g_symbols = gc_copy (g_symbols);
   g_macros = gc_copy (g_macros);
   SCM new = gc_copy (g_stack);
@@ -165,5 +184,31 @@ gc ()
       eputs ("\n");
     }
   g_stack = new;
-  return gc_loop (1);
+  gc_loop (1);
+}
+
+SCM
+gc ()
+{
+  if (g_debug > 4)
+    {
+      eputs ("symbols: ");
+      write_error_ (g_symbols);
+      eputs ("\n");
+      eputs ("R0: ");
+      write_error_ (r0);
+      eputs ("\n");
+    }
+  gc_push_frame ();
+  gc_ ();
+  gc_pop_frame ();
+  if (g_debug > 4)
+    {
+      eputs ("symbols: ");
+      write_error_ (g_symbols);
+      eputs ("\n");
+      eputs ("R0: ");
+      write_error_ (r0);
+      eputs ("\n");
+    }
 }
diff --git a/src/mes.c b/src/mes.c
index 893ffb85..08734a1c 100644
--- a/src/mes.c
+++ b/src/mes.c
@@ -29,12 +29,14 @@
 // take a bit more to run all tests
 int ARENA_SIZE = 400000; // 32b: 1MiB, 64b: 2 MiB
 #if !_POSIX_SOURCE
+//int MAX_ARENA_SIZE = 60000000; // 32b: ~ 300MiB
 int MAX_ARENA_SIZE = 166600000; // 32b: ~ 2GiB
+//int MAX_ARENA_SIZE = 500000000; // 32b: ~ 8GiB
 #else
 int MAX_ARENA_SIZE = 200000000; // 32b: 2.3GiB, 64b: 4.6GiB
 #endif
 
-int GC_SAFETY = 50000;
+int GC_SAFETY = 4000;
 
 char *g_arena = 0;
 typedef int SCM;
@@ -229,10 +231,6 @@ struct scm scm_test = {TSYMBOL, "test",0};
 #include "mes.symbols.h"
 #endif
 
-SCM tmp;
-SCM tmp_num;
-SCM tmp_num2;
-
 struct function g_functions[200];
 int g_function = 0;
 
@@ -306,13 +304,13 @@ int g_function = 0;
 #define NVECTOR(x) g_news[x].vector
 #endif
 
-#define MAKE_CHAR(n) make_cell_ (tmp_num_ (TCHAR), 0, tmp_num2_ (n))
-#define MAKE_CONTINUATION(n) make_cell_ (tmp_num_ (TCONTINUATION), n, g_stack)
-#define MAKE_NUMBER(n) make_cell_ (tmp_num_ (TNUMBER), 0, tmp_num2_ (n))
-#define MAKE_REF(n) make_cell_ (tmp_num_ (TREF), n, 0)
-#define MAKE_STRING(x) make_cell_ (tmp_num_ (TSTRING), x, 0)
-#define MAKE_KEYWORD(x) make_cell_ (tmp_num_ (TKEYWORD), x, 0)
-#define MAKE_MACRO(name, x) make_cell_ (tmp_num_ (TMACRO), STRING (name), x)
+#define MAKE_CHAR(n) make_cell__ (TCHAR, 0, n)
+#define MAKE_CONTINUATION(n) make_cell__ (TCONTINUATION, n, g_stack)
+#define MAKE_NUMBER(n) make_cell__ (TNUMBER, 0, n)
+#define MAKE_REF(n) make_cell__ (TREF, n, 0)
+#define MAKE_STRING(x) make_cell__ (TSTRING, x, 0)
+#define MAKE_KEYWORD(x) make_cell__ (TKEYWORD, x, 0)
+#define MAKE_MACRO(name, x) make_cell__ (TMACRO, STRING (name), x)
 
 #define CAAR(x) CAR (CAR (x))
 #define CADR(x) CAR (CDR (x))
@@ -332,52 +330,29 @@ alloc (int n)
 }
 
 SCM
-tmp_num_ (int x)
+make_cell__ (int type, SCM car, SCM cdr)
 {
-  VALUE (tmp_num) = x;
-  return tmp_num;
-}
-
-SCM
-tmp_num2_ (int x)
-{
-  VALUE (tmp_num2) = x;
-  return tmp_num2;
+  SCM x = alloc (1);
+  TYPE (x) = type;
+  CAR (x) = car;
+  CDR (x) = cdr;
+  return x;
 }
 
 SCM
 make_cell_ (SCM type, SCM car, SCM cdr)
 {
-  SCM x = alloc (1);
   assert (TYPE (type) == TNUMBER);
-  TYPE (x) = VALUE (type);
-  if (VALUE (type) == TCHAR || VALUE (type) == TNUMBER)
-    {
-      if (car)
-        CAR (x) = CAR (car);
-      if (cdr)
-        CDR (x) = CDR (cdr);
-    }
-  else if (VALUE (type) == TFUNCTION)
-    {
-      if (car)
-        CAR (x) = car;
-      if (cdr)
-        CDR (x) = CDR (cdr);
-    }
-  else
-    {
-      CAR (x) = car;
-      CDR (x) = cdr;
-    }
-  return x;
+  int t = VALUE (type);
+  if (t == TCHAR || t == TNUMBER)
+    return make_cell__ (t, car ? CAR (car) : 0, cdr ? CDR (cdr) : 0);
+  return make_cell__ (t, car, cdr);
 }
 
 SCM
 make_symbol_ (SCM s) ///((internal))
 {
-  VALUE (tmp_num) = TSYMBOL;
-  SCM x = make_cell_ (tmp_num, s, 0);
+  SCM x = make_cell__ (TSYMBOL, s, 0);
   g_symbols = cons (x, g_symbols);
   return x;
 }
@@ -451,8 +426,7 @@ arity_ (SCM x)
 SCM
 cons (SCM x, SCM y)
 {
-  VALUE (tmp_num) = TPAIR;
-  return make_cell_ (tmp_num, x, y);
+  return make_cell__ (TPAIR, x, y);
 }
 
 SCM
@@ -514,18 +488,24 @@ acons (SCM key, SCM value, SCM alist)
   return cons (cons (key, value), alist);
 }
 
-SCM
-length (SCM x)
+int
+length__ (SCM x)
 {
   int n = 0;
   while (x != cell_nil)
     {
       n++;
       if (TYPE (x) != TPAIR)
-        return MAKE_NUMBER (-1);
+        return -1;
       x = CDR (x);
     }
-  return MAKE_NUMBER (n);
+  return n;
+}
+
+SCM
+length (SCM x)
+{
+  return MAKE_NUMBER (length__ (x));
 }
 
 SCM apply (SCM, SCM, SCM);
@@ -757,13 +737,13 @@ call_lambda (SCM e, SCM x, SCM aa, SCM a) ///((internal))
 SCM
 make_closure_ (SCM args, SCM body, SCM a) ///((internal))
 {
-  return make_cell_ (tmp_num_ (TCLOSURE), cell_f, cons (cons (cell_circular, a), cons (args, body)));
+  return make_cell__ (TCLOSURE, cell_f, cons (cons (cell_circular, a), cons (args, body)));
 }
 
 SCM
 make_variable_ (SCM var, SCM global_p) ///((internal))
 {
-  return make_cell_ (tmp_num_ (TVARIABLE), var, global_p);
+  return make_cell__ (TVARIABLE, var, global_p);
 }
 
 SCM
@@ -926,7 +906,6 @@ eval_apply ()
   int macro_p;
 
  eval_apply:
-  gc_check ();
   switch (r3)
     {
     case cell_vm_evlis: goto evlis;
@@ -968,7 +947,6 @@ eval_apply ()
     }
 
  evlis:
-  gc_check ();
   if (r1 == cell_nil)
     goto vm_return;
   if (TYPE (r1) != TPAIR)
@@ -983,7 +961,6 @@ eval_apply ()
   goto vm_return;
 
  apply:
-  gc_check ();
   switch (TYPE (CAR (r1)))
     {
     case TFUNCTION:
@@ -1074,7 +1051,6 @@ eval_apply ()
   goto apply;
 
  eval:
-  gc_check ();
   switch (TYPE (r1))
     {
     case TPAIR:
@@ -1108,7 +1084,8 @@ eval_apply ()
               r1 = CADR (x);
               goto eval_apply;
             }
-          case cell_symbol_begin: goto begin;
+          case cell_symbol_begin:
+            goto begin;
           case cell_symbol_lambda:
             {
               r1 = make_closure_ (CADR (r1), CDDR (r1), r0);
@@ -1217,6 +1194,7 @@ eval_apply ()
                   goto vm_return;
                 }
               push_cc (CAR (r1), r1, r0, cell_vm_eval_check_func);
+              gc_check ();
               goto eval;
             eval_check_func:
               push_cc (CDR (r2), r2, r0, cell_vm_eval2);
@@ -1388,8 +1366,7 @@ eval_apply ()
             {
               push_cc (CADR (CAR (r1)), r1, r0, cell_vm_begin_expand_primitive_load);
               goto eval; // FIXME: expand too?!
-            begin_expand_primitive_load:;
-              input; // = current_input_port ();
+            begin_expand_primitive_load:
               if (TYPE (r1) == TNUMBER && VALUE (r1) == 0)
                 ;
               else if (TYPE (r1) == TSTRING)
@@ -1421,7 +1398,6 @@ eval_apply ()
         }
       r1 = r2;
       expand_variable (CAR (r1), cell_nil);
-      //eputs ("expanded r1="); write_error_ (CAR (r1)); eputs ("\n");
       push_cc (CAR (r1), r1, r0, cell_vm_begin_expand_eval);
       goto eval;
     begin_expand_eval:
@@ -1497,18 +1473,6 @@ mes_g_stack (SCM a) ///((internal))
 
 // Environment setup
 
-SCM
-make_tmps (struct scm* cells)
-{
-  tmp = g_free++;
-  cells[tmp].type = TCHAR;
-  tmp_num = g_free++;
-  cells[tmp_num].type = TNUMBER;
-  tmp_num2 = g_free++;
-  cells[tmp_num2].type = TNUMBER;
-  return 0;
-}
-
 #include "posix.c"
 #include "math.c"
 #include "lib.c"
@@ -1520,15 +1484,10 @@ SCM
 gc_init_cells () ///((internal))
 {
   g_cells = (struct scm *)malloc (2*ARENA_SIZE*sizeof (struct scm));
-
   TYPE (0) = TVECTOR;
   LENGTH (0) = 1000;
   VECTOR (0) = 0;
-#if 0 //__MESC__
-  g_cells += sizeof (struct scm);
-#else
   g_cells++;
-#endif
   TYPE (0) = TCHAR;
   VALUE (0) = 'c';
   return 0;
@@ -1537,23 +1496,11 @@ gc_init_cells () ///((internal))
 SCM
 gc_init_news () ///((internal))
 {
-#if 0 //__MESC__
-  char *p = g_cells;
-  p -= sizeof (struct scm);
-  p += ARENA_SIZE * sizeof (struct scm);
-  g_news = p;
-#else
   g_news = g_cells-1 + ARENA_SIZE;
-#endif
-
   NTYPE (0) = TVECTOR;
   NLENGTH (0) = 1000;
   NVECTOR (0) = 0;
-#if 0 //__MESC__
-  g_news += sizeof (struct scm);
-#else
   g_news++;
-#endif
   NTYPE (0) = TCHAR;
   NVALUE (0) = 'n';
   return 0;
@@ -1571,9 +1518,7 @@ mes_symbols () ///((internal))
 #include "mes.symbols.i"
 #endif
 
-  g_symbol_max = g_free;
-  make_tmps (g_cells);
-
+  g_symbol_max = g_free++;
   g_symbols = 0;
   for (int i=1; i<g_symbol_max; i++)
     g_symbols = cons (i, g_symbols);
@@ -1845,7 +1790,6 @@ main (int argc, char *argv[])
     MAX_ARENA_SIZE = atoi (p);
   if (p = getenv ("MES_ARENA"))
     ARENA_SIZE = atoi (p);
-  GC_SAFETY = ARENA_SIZE / 400;
   if (p = getenv ("MES_SAFETY"))
     GC_SAFETY = atoi (p);
   if (argc > 1 && !strcmp (argv[1], "--help"))
@@ -1900,6 +1844,7 @@ main (int argc, char *argv[])
     {
       eputs ("\ngc stats: [");
       eputs (itoa (g_free));
+      MAX_ARENA_SIZE = 0;
       gc (g_stack);
       eputs (" => ");
       eputs (itoa (g_free));
diff --git a/src/vector.c b/src/vector.c
index 36a9e09c..ad4cac91 100644
--- a/src/vector.c
+++ b/src/vector.c
@@ -19,16 +19,20 @@
  */
 
 SCM
-make_vector_ (SCM n)
+make_vector__ (int k)
 {
-  int k = VALUE (n);
-  VALUE (tmp_num) = TVECTOR;
   SCM v = alloc (k);
-  SCM x = make_cell_ (tmp_num, k, v);
+  SCM x = make_cell__ (TVECTOR, k, v);
   for (int i=0; i<k; i++) g_cells[v+i] = g_cells[vector_entry (cell_unspecified)];
   return x;
 }
 
+SCM
+make_vector_ (SCM n)
+{
+  return make_vector__ (VALUE (n));
+}
+
 SCM
 vector_length (SCM x)
 {
@@ -71,8 +75,8 @@ vector_set_x (SCM x, SCM i, SCM e)
 SCM
 list_to_vector (SCM x)
 {
-  VALUE (tmp_num) = VALUE (length (x));
-  SCM v = make_vector_ (tmp_num);
+
+  SCM v = make_vector__ (length__ (x));
   SCM p = VECTOR (v);
   while (x != cell_nil)
     {
diff --git a/tests/psyntax.test b/tests/psyntax.test
index d0d3c2fe..441e782d 100755
--- a/tests/psyntax.test
+++ b/tests/psyntax.test
@@ -1,7 +1,7 @@
 #! /bin/sh
 # -*-scheme-*-
 MES=${MES-$(dirname $0)/../src/mes}
-#export MES_ARENA=${MES_ARENA-40000}
+#export MES_ARENA=${MES_ARENA-200000}
 $MES $MES_FLAGS "$@" < $0
 exit $?
 !#