diff --git a/extlib/benz/codegen.c b/extlib/benz/codegen.c
index a51b6ab1..44895678 100644
--- a/extlib/benz/codegen.c
+++ b/extlib/benz/codegen.c
@@ -121,7 +121,7 @@ expand_list(pic_state *pic, pic_value obj, struct pic_env *env, pic_value deferr
 static pic_value
 expand_defer(pic_state *pic, pic_value expr, pic_value deferred)
 {
-  pic_value skel = pic_list1(pic, pic_invalid_value()); /* (#<invalid>) */
+  pic_value skel = pic_cons(pic, pic_invalid_value(), pic_invalid_value());
 
   pic_set_car(pic, deferred, pic_acons(pic, expr, skel, pic_car(pic, deferred)));
 
@@ -328,7 +328,7 @@ analyzer_scope_init(pic_state *pic, analyze_scope *scope, pic_value formal, anal
 
   scope->up = up;
   scope->depth = up ? up->depth + 1 : 0;
-  scope->defer = pic_nil_value();
+  scope->defer = pic_list1(pic, pic_nil_value());
 }
 
 static void
@@ -378,7 +378,7 @@ define_var(pic_state *pic, analyze_scope *scope, pic_sym *sym)
   kh_put(a, &scope->locals, sym, &ret);
 }
 
-static pic_value analyze(pic_state *, analyze_scope *, pic_value, bool);
+static pic_value analyze(pic_state *, analyze_scope *, pic_value);
 static pic_value analyze_lambda(pic_state *, analyze_scope *, pic_value);
 
 static pic_value
@@ -400,12 +400,9 @@ analyze_var(pic_state *pic, analyze_scope *scope, pic_sym *sym)
 static pic_value
 analyze_defer(pic_state *pic, analyze_scope *scope, pic_value form)
 {
-  pic_sym *sNOWHERE = pic_intern_cstr(pic, "<<nowhere>>");
-  pic_value skel;
+  pic_value skel = pic_cons(pic, pic_invalid_value(), pic_invalid_value());
 
-  skel = pic_list2(pic, pic_obj_value(pic->sGREF), pic_obj_value(sNOWHERE));
-
-  pic_push(pic, pic_cons(pic, skel, form), scope->defer);
+  pic_set_car(pic, scope->defer, pic_acons(pic, form, skel, pic_car(pic, scope->defer)));
 
   return skel;
 }
@@ -413,20 +410,20 @@ analyze_defer(pic_state *pic, analyze_scope *scope, pic_value form)
 static void
 analyze_deferred(pic_state *pic, analyze_scope *scope)
 {
-  pic_value defer, it, skel, form, val;
+  pic_value defer, val, src, dst, it;
+
+  scope->defer = pic_car(pic, scope->defer);
 
   pic_for_each (defer, pic_reverse(pic, scope->defer), it) {
-    skel = pic_car(pic, defer);
-    form = pic_cdr(pic, defer);
+    src = pic_car(pic, defer);
+    dst = pic_cdr(pic, defer);
 
-    val = analyze_lambda(pic, scope, form);
+    val = analyze_lambda(pic, scope, src);
 
     /* copy */
-    pic_pair_ptr(skel)->car = pic_car(pic, val);
-    pic_pair_ptr(skel)->cdr = pic_cdr(pic, val);
+    pic_set_car(pic, dst, pic_car(pic, val));
+    pic_set_cdr(pic, dst, pic_cdr(pic, val));
   }
-
-  scope->defer = pic_nil_value();
 }
 
 static pic_value
@@ -444,7 +441,7 @@ analyze_lambda(pic_state *pic, analyze_scope *up, pic_value form)
   analyzer_scope_init(pic, scope, formals, up);
 
   /* analyze body */
-  body = analyze(pic, scope, body, true);
+  body = analyze(pic, scope, body);
   analyze_deferred(pic, scope);
 
   args = pic_make_vec(pic, kh_size(&scope->args));
@@ -472,243 +469,37 @@ analyze_lambda(pic_state *pic, analyze_scope *up, pic_value form)
 
   analyzer_scope_destroy(pic, scope);
 
-  return pic_list6(pic, pic_obj_value(pic->sLAMBDA), rest, pic_obj_value(args), pic_obj_value(locals), pic_obj_value(captures), body);
+  return pic_list6(pic, pic_obj_value(pic->uLAMBDA), rest, pic_obj_value(args), pic_obj_value(locals), pic_obj_value(captures), body);
+}
+
+static pic_value
+analyze_list(pic_state *pic, analyze_scope *scope, pic_value obj)
+{
+  pic_value seq = pic_nil_value(), val, it;
+
+  pic_for_each (val, obj, it) {
+    pic_push(pic, analyze(pic, scope, val), seq);
+  }
+
+  return pic_reverse(pic, seq);
 }
 
 static pic_value
 analyze_define(pic_state *pic, analyze_scope *scope, pic_value obj)
 {
-  pic_value var, val;
-
   define_var(pic, scope, pic_sym_ptr(pic_list_ref(pic, obj, 1)));
 
-  var = analyze(pic, scope, pic_list_ref(pic, obj, 1), false);
-  val = analyze(pic, scope, pic_list_ref(pic, obj, 2), false);
-
-  return pic_list3(pic, pic_obj_value(pic->sSETBANG), var, val);
+  return pic_cons(pic, pic_car(pic, obj), analyze_list(pic, scope, pic_cdr(pic, obj)));
 }
 
 static pic_value
-analyze_if(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
+analyze_call(pic_state *pic, analyze_scope *scope, pic_value obj)
 {
-  pic_value cond, if_true, if_false;
-
-  if_true = pic_list_ref(pic, obj, 2);
-  if_false = pic_list_ref(pic, obj, 3);
-
-  cond = analyze(pic, scope, pic_list_ref(pic, obj, 1), false);
-  if_true = analyze(pic, scope, if_true, tailpos);
-  if_false = analyze(pic, scope, if_false, tailpos);
-
-  return pic_list4(pic, pic_obj_value(pic->sIF), cond, if_true, if_false);
+  return pic_cons(pic, pic_obj_value(pic->sCALL), analyze_list(pic, scope, obj));
 }
 
 static pic_value
-analyze_begin(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
-{
-  pic_value beg1, beg2;
-
-  beg1 = pic_list_ref(pic, obj, 1);
-  beg2 = pic_list_ref(pic, obj, 2);
-
-  beg1 = analyze(pic, scope, beg1, false);
-  beg2 = analyze(pic, scope, beg2, tailpos);
-
-  return pic_list3(pic, pic_obj_value(pic->sBEGIN), beg1, beg2);
-}
-
-static pic_value
-analyze_set(pic_state *pic, analyze_scope *scope, pic_value obj)
-{
-  pic_value var, val;
-
-  var = pic_list_ref(pic, obj, 1);
-  val = pic_list_ref(pic, obj, 2);
-
-  var = analyze(pic, scope, var, false);
-  val = analyze(pic, scope, val, false);
-
-  return pic_list3(pic, pic_obj_value(pic->sSETBANG), var, val);
-}
-
-static pic_value
-analyze_quote(pic_state *pic, pic_value obj)
-{
-  return pic_list2(pic, pic_obj_value(pic->sQUOTE), pic_list_ref(pic, obj, 1));
-}
-
-#define ARGC_ASSERT_GE(n, name) do {                                    \
-    if (pic_length(pic, obj) < (n) + 1) {                               \
-      pic_errorf(pic,                                                   \
-        #name ": wrong number of arguments (%d for at least %d)",       \
-                 pic_length(pic, obj) - 1,                              \
-                 n);                                                    \
-    }                                                                   \
-  } while (0)
-
-#define FOLD_ARGS(sym) do {                                     \
-    obj = analyze(pic, scope, pic_car(pic, args), false);       \
-    pic_for_each (arg, pic_cdr(pic, args), it) {                \
-      obj = pic_list3(pic, pic_obj_value(sym), obj,             \
-                      analyze(pic, scope, arg, false));         \
-    }                                                           \
-  } while (0)
-
-static pic_value
-analyze_add(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
-{
-  pic_value args, arg, it;
-
-  ARGC_ASSERT_GE(0, "+");
-  switch (pic_length(pic, obj)) {
-  case 1:
-    return pic_list2(pic, pic_obj_value(pic->sQUOTE), pic_int_value(0));
-  case 2:
-    return analyze(pic, scope, pic_car(pic, pic_cdr(pic, obj)), tailpos);
-  default:
-    args = pic_cdr(pic, obj);
-    FOLD_ARGS(pic->sADD);
-    return obj;
-  }
-}
-
-static pic_value
-analyze_sub(pic_state *pic, analyze_scope *scope, pic_value obj)
-{
-  pic_value args, arg, it;
-
-  ARGC_ASSERT_GE(1, "-");
-  switch (pic_length(pic, obj)) {
-  case 2:
-    return pic_list2(pic, pic_obj_value(pic->sMINUS),
-                     analyze(pic, scope, pic_car(pic, pic_cdr(pic, obj)), false));
-  default:
-    args = pic_cdr(pic, obj);
-    FOLD_ARGS(pic->sSUB);
-    return obj;
-  }
-}
-
-static pic_value
-analyze_mul(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
-{
-  pic_value args, arg, it;
-
-  ARGC_ASSERT_GE(0, "*");
-  switch (pic_length(pic, obj)) {
-  case 1:
-    return pic_list2(pic, pic_obj_value(pic->sQUOTE), pic_int_value(1));
-  case 2:
-    return analyze(pic, scope, pic_car(pic, pic_cdr(pic, obj)), tailpos);
-  default:
-    args = pic_cdr(pic, obj);
-    FOLD_ARGS(pic->sMUL);
-    return obj;
-  }
-}
-
-static pic_value
-analyze_div(pic_state *pic, analyze_scope *scope, pic_value obj)
-{
-  pic_value args, arg, it;
-
-  ARGC_ASSERT_GE(1, "/");
-  switch (pic_length(pic, obj)) {
-  case 2:
-    args = pic_cdr(pic, obj);
-#if PIC_ENABLE_FLOAT
-    obj = pic_list3(pic, pic_car(pic, obj), pic_float_value(1), pic_car(pic, args));
-#else
-    obj = pic_list3(pic, pic_car(pic, obj), pic_int_value(1), pic_car(pic, args));
-#endif
-    return analyze(pic, scope, obj, false);
-  default:
-    args = pic_cdr(pic, obj);
-    FOLD_ARGS(pic->sDIV);
-    return obj;
-  }
-}
-
-static pic_value
-analyze_call(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
-{
-  pic_value seq, elt, it;
-  pic_sym *call;
-
-  if (! tailpos) {
-    call = pic->sCALL;
-  } else {
-    call = pic->sTAILCALL;
-  }
-  seq = pic_list1(pic, pic_obj_value(call));
-  pic_for_each (elt, obj, it) {
-    seq = pic_cons(pic, analyze(pic, scope, elt, false), seq);
-  }
-  return pic_reverse(pic, seq);
-}
-
-static pic_value
-analyze_values(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
-{
-  pic_value v, seq, it;
-
-  if (! tailpos) {
-    return analyze_call(pic, scope, obj, false);
-  }
-
-  seq = pic_list1(pic, pic_obj_value(pic->sRETURN));
-  pic_for_each (v, pic_cdr(pic, obj), it) {
-    seq = pic_cons(pic, analyze(pic, scope, v, false), seq);
-  }
-  return pic_reverse(pic, seq);
-}
-
-static pic_value
-analyze_call_with_values(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
-{
-  pic_value prod, cnsm;
-  pic_sym *call;
-
-  if (pic_length(pic, obj) != 3) {
-    pic_errorf(pic, "call-with-values: wrong number of arguments (%d for 2)", pic_length(pic, obj) - 1);
-  }
-
-  if (! tailpos) {
-    call = pic->sCALL_WITH_VALUES;
-  } else {
-    call = pic->sTAILCALL_WITH_VALUES;
-  }
-  prod = analyze(pic, scope, pic_list_ref(pic, obj, 1), false);
-  cnsm = analyze(pic, scope, pic_list_ref(pic, obj, 2), false);
-  return pic_list3(pic, pic_obj_value(call), prod, cnsm);
-}
-
-#define ARGC_ASSERT(n, name) do {                                       \
-    if (pic_length(pic, obj) != (n) + 1) {                              \
-      pic_errorf(pic, #name ": wrong number of arguments (%d for %d)",  \
-                 pic_length(pic, obj) - 1, n);                          \
-    }                                                                   \
-  } while (0)
-
-#define ARGC_ASSERT_WITH_FALLBACK(n) do {       \
-    if (pic_length(pic, obj) != (n) + 1) {      \
-      goto fallback;                            \
-    }						\
-  } while (0)
-
-#define CONSTRUCT_OP1(op)                                               \
-  pic_list2(pic,                                                        \
-            pic_obj_value(op),                                          \
-            analyze(pic, scope, pic_list_ref(pic, obj, 1), false))
-
-#define CONSTRUCT_OP2(op)                                               \
-  pic_list3(pic,                                                        \
-            pic_obj_value(op),                                          \
-            analyze(pic, scope, pic_list_ref(pic, obj, 1), false),      \
-            analyze(pic, scope, pic_list_ref(pic, obj, 2), false))
-
-static pic_value
-analyze_node(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
+analyze_node(pic_state *pic, analyze_scope *scope, pic_value obj)
 {
   switch (pic_type(obj)) {
   case PIC_TT_SYMBOL: {
@@ -731,116 +522,31 @@ analyze_node(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
       else if (sym == pic->uLAMBDA) {
         return analyze_defer(pic, scope, obj);
       }
-      else if (sym == pic->uIF) {
-        return analyze_if(pic, scope, obj, tailpos);
-      }
-      else if (sym == pic->uBEGIN) {
-        return analyze_begin(pic, scope, obj, tailpos);
-      }
-      else if (sym == pic->uSETBANG) {
-        return analyze_set(pic, scope, obj);
-      }
       else if (sym == pic->uQUOTE) {
-        return analyze_quote(pic, obj);
+        return obj;
       }
-      else if (sym == pic->uCONS) {
-	ARGC_ASSERT(2, "cons");
-        return CONSTRUCT_OP2(pic->sCONS);
-      }
-      else if (sym == pic->uCAR) {
-	ARGC_ASSERT(1, "car");
-        return CONSTRUCT_OP1(pic->sCAR);
-      }
-      else if (sym == pic->uCDR) {
-	ARGC_ASSERT(1, "cdr");
-        return CONSTRUCT_OP1(pic->sCDR);
-      }
-      else if (sym == pic->uNILP) {
-	ARGC_ASSERT(1, "nil?");
-        return CONSTRUCT_OP1(pic->sNILP);
-      }
-      else if (sym == pic->uSYMBOLP) {
-        ARGC_ASSERT(1, "symbol?");
-        return CONSTRUCT_OP1(pic->sSYMBOLP);
-      }
-      else if (sym == pic->uPAIRP) {
-        ARGC_ASSERT(1, "pair?");
-        return CONSTRUCT_OP1(pic->sPAIRP);
-      }
-      else if (sym == pic->uADD) {
-        return analyze_add(pic, scope, obj, tailpos);
-      }
-      else if (sym == pic->uSUB) {
-        return analyze_sub(pic, scope, obj);
-      }
-      else if (sym == pic->uMUL) {
-        return analyze_mul(pic, scope, obj, tailpos);
-      }
-      else if (sym == pic->uDIV) {
-        return analyze_div(pic, scope, obj);
-      }
-      else if (sym == pic->uEQ) {
-	ARGC_ASSERT_WITH_FALLBACK(2);
-        return CONSTRUCT_OP2(pic->sEQ);
-      }
-      else if (sym == pic->uLT) {
-	ARGC_ASSERT_WITH_FALLBACK(2);
-        return CONSTRUCT_OP2(pic->sLT);
-      }
-      else if (sym == pic->uLE) {
-	ARGC_ASSERT_WITH_FALLBACK(2);
-        return CONSTRUCT_OP2(pic->sLE);
-      }
-      else if (sym == pic->uGT) {
-	ARGC_ASSERT_WITH_FALLBACK(2);
-        return CONSTRUCT_OP2(pic->sGT);
-      }
-      else if (sym == pic->uGE) {
-	ARGC_ASSERT_WITH_FALLBACK(2);
-        return CONSTRUCT_OP2(pic->sGE);
-      }
-      else if (sym == pic->uNOT) {
-        ARGC_ASSERT(1, "not");
-        return CONSTRUCT_OP1(pic->sNOT);
-      }
-      else if (sym == pic->uVALUES) {
-        return analyze_values(pic, scope, obj, tailpos);
-      }
-      else if (sym == pic->uCALL_WITH_VALUES) {
-        return analyze_call_with_values(pic, scope, obj, tailpos);
+      else if (sym == pic->uBEGIN || sym == pic->uSETBANG || sym == pic->uIF) {
+        return pic_cons(pic, pic_car(pic, obj), analyze_list(pic, scope, pic_cdr(pic, obj)));
       }
     }
-    fallback:
 
-    return analyze_call(pic, scope, obj, tailpos);
+    return analyze_call(pic, scope, obj);
   }
   default:
-    return pic_list2(pic, pic_obj_value(pic->sQUOTE), obj);
+    return pic_list2(pic, pic_obj_value(pic->uQUOTE), obj);
   }
 }
 
 static pic_value
-analyze(pic_state *pic, analyze_scope *scope, pic_value obj, bool tailpos)
+analyze(pic_state *pic, analyze_scope *scope, pic_value obj)
 {
   size_t ai = pic_gc_arena_preserve(pic);
   pic_value res;
-  pic_sym *tag;
 
-  res = analyze_node(pic, scope, obj, tailpos);
-
-  tag = pic_sym_ptr(pic_car(pic, res));
-  if (tailpos) {
-    if (tag == pic->sIF || tag == pic->sBEGIN || tag == pic->sTAILCALL || tag == pic->sTAILCALL_WITH_VALUES || tag == pic->sRETURN) {
-      /* pass through */
-    }
-    else {
-      res = pic_list2(pic, pic_obj_value(pic->sRETURN), res);
-    }
-  }
+  res = analyze_node(pic, scope, obj);
 
   pic_gc_arena_restore(pic, ai);
   pic_gc_protect(pic, res);
-  pic_gc_protect(pic, scope->defer);
   return res;
 }
 
@@ -851,7 +557,7 @@ pic_analyze(pic_state *pic, pic_value obj)
 
   analyzer_scope_init(pic, scope, pic_nil_value(), NULL);
 
-  obj = analyze(pic, scope, obj, true);
+  obj = analyze(pic, scope, obj);
 
   analyze_deferred(pic, scope);
 
@@ -973,6 +679,8 @@ codegen_context_destroy(pic_state *pic, codegen_context *cxt)
     cxt->clen++;                                \
   } while (0)                                   \
 
+#define emit_ret(pic, cxt, tailpos) if (tailpos) emit_i(pic, cxt, OP_RET, 1)
+
 static void
 create_activation(pic_state *pic, codegen_context *cxt)
 {
@@ -1054,16 +762,96 @@ index_symbol(pic_state *pic, codegen_context *cxt, pic_sym *sym)
   return i;
 }
 
-static void codegen(pic_state *, codegen_context *, pic_value);
+static void codegen(pic_state *, codegen_context *, pic_value, bool);
 
-static struct pic_irep *
-codegen_lambda(pic_state *pic, codegen_context *up, pic_value obj)
+static void
+codegen_ref(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
 {
-  codegen_context c, *cxt = &c;
+  pic_sym *sym;
+
+  sym = pic_sym_ptr(pic_car(pic, obj));
+  if (sym == pic->sGREF) {
+    emit_i(pic, cxt, OP_GREF, index_symbol(pic, cxt, pic_sym_ptr(pic_list_ref(pic, obj, 1))));
+    emit_ret(pic, cxt, tailpos);
+  }
+  else if (sym == pic->sCREF) {
+    pic_sym *name;
+    int depth;
+
+    depth = pic_int(pic_list_ref(pic, obj, 1));
+    name  = pic_sym_ptr(pic_list_ref(pic, obj, 2));
+    emit_r(pic, cxt, OP_CREF, depth, index_capture(cxt, name, depth));
+    emit_ret(pic, cxt, tailpos);
+  }
+  else if (sym == pic->sLREF) {
+    pic_sym *name;
+    int i;
+
+    name = pic_sym_ptr(pic_list_ref(pic, obj, 1));
+    if ((i = index_capture(cxt, name, 0)) != -1) {
+      emit_i(pic, cxt, OP_LREF, i + (int)cxt->args->len + (int)cxt->locals->len + 1);
+      emit_ret(pic, cxt, tailpos);
+    } else {
+      emit_i(pic, cxt, OP_LREF, index_local(cxt, name));
+      emit_ret(pic, cxt, tailpos);
+    }
+  }
+}
+
+static void
+codegen_set(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
+{
+  pic_value var, val;
+  pic_sym *type;
+
+  val = pic_list_ref(pic, obj, 2);
+  codegen(pic, cxt, val, false);
+
+  var = pic_list_ref(pic, obj, 1);
+  type = pic_sym_ptr(pic_list_ref(pic, var, 0));
+  if (type == pic->sGREF) {
+    emit_i(pic, cxt, OP_GSET, index_symbol(pic, cxt, pic_sym_ptr(pic_list_ref(pic, var, 1))));
+    emit_n(pic, cxt, OP_PUSHUNDEF);
+    emit_ret(pic, cxt, tailpos);
+  }
+  else if (type == pic->sCREF) {
+    pic_sym *name;
+    int depth;
+
+    depth = pic_int(pic_list_ref(pic, var, 1));
+    name  = pic_sym_ptr(pic_list_ref(pic, var, 2));
+    emit_r(pic, cxt, OP_CSET, depth, index_capture(cxt, name, depth));
+    emit_n(pic, cxt, OP_PUSHUNDEF);
+    emit_ret(pic, cxt, tailpos);
+  }
+  else if (type == pic->sLREF) {
+    pic_sym *name;
+    int i;
+
+    name = pic_sym_ptr(pic_list_ref(pic, var, 1));
+    if ((i = index_capture(cxt, name, 0)) != -1) {
+      emit_i(pic, cxt, OP_LSET, i + (int)cxt->args->len + (int)cxt->locals->len + 1);
+      emit_n(pic, cxt, OP_PUSHUNDEF);
+      emit_ret(pic, cxt, tailpos);
+    } else {
+      emit_i(pic, cxt, OP_LSET, index_local(cxt, name));
+      emit_n(pic, cxt, OP_PUSHUNDEF);
+      emit_ret(pic, cxt, tailpos);
+    }
+  }
+}
+
+static void
+codegen_lambda(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
+{
+  codegen_context c, *inner_cxt = &c;
   pic_value rest_opt, body;
   pic_sym *rest = NULL;
   pic_vec *args, *locals, *captures;
 
+  check_irep_size(pic, cxt);
+
+  /* extract arguments */
   rest_opt = pic_list_ref(pic, obj, 1);
   if (pic_sym_p(rest_opt)) {
     rest = pic_sym_ptr(rest_opt);
@@ -1073,272 +861,174 @@ codegen_lambda(pic_state *pic, codegen_context *up, pic_value obj)
   captures = pic_vec_ptr(pic_list_ref(pic, obj, 4));
   body = pic_list_ref(pic, obj, 5);
 
-  /* inner environment */
-  codegen_context_init(pic, cxt, up, rest, args, locals, captures);
-  {
-    /* body */
-    codegen(pic, cxt, body);
-  }
-  return codegen_context_destroy(pic, cxt);
+  /* emit irep */
+  codegen_context_init(pic, inner_cxt, cxt, rest, args, locals, captures);
+  codegen(pic, inner_cxt, body, true);
+  cxt->irep[cxt->ilen] = codegen_context_destroy(pic, inner_cxt);
+
+  /* emit OP_LAMBDA */
+  emit_i(pic, cxt, OP_LAMBDA, cxt->ilen++);
+  emit_ret(pic, cxt, tailpos);
 }
 
 static void
-codegen(pic_state *pic, codegen_context *cxt, pic_value obj)
+codegen_if(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
+{
+  int s, t;
+
+  codegen(pic, cxt, pic_list_ref(pic, obj, 1), false);
+
+  s = (int)cxt->clen;
+
+  emit_n(pic, cxt, OP_JMPIF);
+
+  /* if false branch */
+  codegen(pic, cxt, pic_list_ref(pic, obj, 3), tailpos);
+
+  t = (int)cxt->clen;
+
+  emit_n(pic, cxt, OP_JMP);
+
+  cxt->code[s].u.i = (int)cxt->clen - s;
+
+  /* if true branch */
+  codegen(pic, cxt, pic_list_ref(pic, obj, 2), tailpos);
+  cxt->code[t].u.i = (int)cxt->clen - t;
+}
+
+static void
+codegen_begin(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
+{
+  codegen(pic, cxt, pic_list_ref(pic, obj, 1), false);
+  emit_n(pic, cxt, OP_POP);
+  codegen(pic, cxt, pic_list_ref(pic, obj, 2), tailpos);
+}
+
+static void
+codegen_quote(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
+{
+  int pidx;
+
+  obj = pic_list_ref(pic, obj, 1);
+  switch (pic_type(obj)) {
+  case PIC_TT_BOOL:
+    emit_n(pic, cxt, (pic_true_p(obj) ? OP_PUSHTRUE : OP_PUSHFALSE));
+    emit_ret(pic, cxt, tailpos);
+    break;
+  case PIC_TT_INT:
+    emit_i(pic, cxt, OP_PUSHINT, pic_int(obj));
+    emit_ret(pic, cxt, tailpos);
+    break;
+  case PIC_TT_NIL:
+    emit_n(pic, cxt, OP_PUSHNIL);
+    emit_ret(pic, cxt, tailpos);
+    break;
+  case PIC_TT_CHAR:
+    emit_c(pic, cxt, OP_PUSHCHAR, pic_char(obj));
+    emit_ret(pic, cxt, tailpos);
+    break;
+  default:
+    check_pool_size(pic, cxt);
+    pidx = (int)cxt->plen++;
+    cxt->pool[pidx] = obj;
+    emit_i(pic, cxt, OP_PUSHCONST, pidx);
+    emit_ret(pic, cxt, tailpos);
+    break;
+  }
+}
+
+static bool
+codegen_call_vm(pic_state *pic, codegen_context *cxt, pic_value proc, size_t len, bool tailpos)
+{
+  pic_sym *sym;
+
+  if (pic_sym_ptr(pic_list_ref(pic, proc, 0)) == pic->sGREF) {
+
+#define VM(uid, op)                             \
+    if (sym == uid) {                           \
+      emit_n(pic, cxt, op);                     \
+      emit_ret(pic, cxt, tailpos);              \
+      return true;                              \
+    }
+
+    /*
+      TODO:
+      - call-with-values, values, >, >=
+      - more than 2 arguments for add, sub, mul, ...
+    */
+
+    sym = pic_sym_ptr(pic_list_ref(pic, proc, 1));
+
+    if (len == 3) {             /* binary operator */
+      VM(pic->uCONS, OP_CONS)
+      VM(pic->uADD, OP_ADD)
+      VM(pic->uSUB, OP_SUB)
+      VM(pic->uMUL, OP_MUL)
+      VM(pic->uDIV, OP_DIV)
+      VM(pic->uEQ, OP_EQ)
+      VM(pic->uLT, OP_LT)
+      VM(pic->uLE, OP_LE)
+    }
+    if (len == 2) {             /* unary operator */
+      VM(pic->uCAR, OP_CAR)
+      VM(pic->uCDR, OP_CDR)
+      VM(pic->uNILP, OP_NILP)
+      VM(pic->uSYMBOLP, OP_SYMBOLP)
+      VM(pic->uPAIRP, OP_PAIRP)
+      VM(pic->uSUB, OP_MINUS)
+      VM(pic->uNOT, OP_NOT)
+    }
+  }
+  return false;
+}
+
+static void
+codegen_call(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
+{
+  int len = (int)pic_length(pic, obj);
+  pic_value elt, it;
+
+  pic_for_each (elt, pic_cdr(pic, obj), it) {
+    codegen(pic, cxt, elt, false);
+  }
+
+  if (codegen_call_vm(pic, cxt, pic_list_ref(pic, obj, 1), len - 1, tailpos)) {
+    return;
+  }
+
+  emit_i(pic, cxt, (tailpos ? OP_TAILCALL : OP_CALL), len - 1);
+}
+
+static void
+codegen(pic_state *pic, codegen_context *cxt, pic_value obj, bool tailpos)
 {
   pic_sym *sym;
 
   sym = pic_sym_ptr(pic_car(pic, obj));
-  if (sym == pic->sGREF) {
-    emit_i(pic, cxt, OP_GREF, index_symbol(pic, cxt, pic_sym_ptr(pic_list_ref(pic, obj, 1))));
-    return;
-  } else if (sym == pic->sCREF) {
-    pic_sym *name;
-    int depth;
-
-    depth = pic_int(pic_list_ref(pic, obj, 1));
-    name  = pic_sym_ptr(pic_list_ref(pic, obj, 2));
-    emit_r(pic, cxt, OP_CREF, depth, index_capture(cxt, name, depth));
-    return;
-  } else if (sym == pic->sLREF) {
-    pic_sym *name;
-    int i;
-
-    name = pic_sym_ptr(pic_list_ref(pic, obj, 1));
-    if ((i = index_capture(cxt, name, 0)) != -1) {
-      emit_i(pic, cxt, OP_LREF, i + (int)cxt->args->len + (int)cxt->locals->len + 1);
-      return;
-    }
-    emit_i(pic, cxt, OP_LREF, index_local(cxt, name));
-    return;
-  } else if (sym == pic->sSETBANG) {
-    pic_value var, val;
-    pic_sym *type;
-
-    val = pic_list_ref(pic, obj, 2);
-    codegen(pic, cxt, val);
-
-    var = pic_list_ref(pic, obj, 1);
-    type = pic_sym_ptr(pic_list_ref(pic, var, 0));
-    if (type == pic->sGREF) {
-      emit_i(pic, cxt, OP_GSET, index_symbol(pic, cxt, pic_sym_ptr(pic_list_ref(pic, var, 1))));
-      emit_n(pic, cxt, OP_PUSHUNDEF);
-      return;
-    }
-    else if (type == pic->sCREF) {
-      pic_sym *name;
-      int depth;
-
-      depth = pic_int(pic_list_ref(pic, var, 1));
-      name  = pic_sym_ptr(pic_list_ref(pic, var, 2));
-      emit_r(pic, cxt, OP_CSET, depth, index_capture(cxt, name, depth));
-      emit_n(pic, cxt, OP_PUSHUNDEF);
-      return;
-    }
-    else if (type == pic->sLREF) {
-      pic_sym *name;
-      int i;
-
-      name = pic_sym_ptr(pic_list_ref(pic, var, 1));
-      if ((i = index_capture(cxt, name, 0)) != -1) {
-        emit_i(pic, cxt, OP_LSET, i + (int)cxt->args->len + (int)cxt->locals->len + 1);
-        emit_n(pic, cxt, OP_PUSHUNDEF);
-        return;
-      }
-      emit_i(pic, cxt, OP_LSET, index_local(cxt, name));
-      emit_n(pic, cxt, OP_PUSHUNDEF);
-      return;
-    }
+  if (sym == pic->sGREF || sym == pic->sCREF || sym == pic->sLREF) {
+    codegen_ref(pic, cxt, obj, tailpos);
   }
-  else if (sym == pic->sLAMBDA) {
-    int k;
-
-    check_irep_size(pic, cxt);
-    k = (int)cxt->ilen++;
-    emit_i(pic, cxt, OP_LAMBDA, k);
-
-    cxt->irep[k] = codegen_lambda(pic, cxt, obj);
-    return;
+  else if (sym == pic->uSETBANG || sym == pic->uDEFINE) {
+    codegen_set(pic, cxt, obj, tailpos);
   }
-  else if (sym == pic->sIF) {
-    int s, t;
-
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-
-    s = (int)cxt->clen;
-
-    emit_n(pic, cxt, OP_JMPIF);
-
-    /* if false branch */
-    codegen(pic, cxt, pic_list_ref(pic, obj, 3));
-
-    t = (int)cxt->clen;
-
-    emit_n(pic, cxt, OP_JMP);
-
-    cxt->code[s].u.i = (int)cxt->clen - s;
-
-    /* if true branch */
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    cxt->code[t].u.i = (int)cxt->clen - t;
-    return;
+  else if (sym == pic->uLAMBDA) {
+    codegen_lambda(pic, cxt, obj, tailpos);
   }
-  else if (sym == pic->sBEGIN) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_POP);
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    return;
+  else if (sym == pic->uIF) {
+    codegen_if(pic, cxt, obj, tailpos);
   }
-  else if (sym == pic->sQUOTE) {
-    int pidx;
-
-    obj = pic_list_ref(pic, obj, 1);
-    switch (pic_type(obj)) {
-    case PIC_TT_BOOL:
-      emit_n(pic, cxt, (pic_true_p(obj) ? OP_PUSHTRUE : OP_PUSHFALSE));
-      return;
-    case PIC_TT_INT:
-      emit_i(pic, cxt, OP_PUSHINT, pic_int(obj));
-      return;
-    case PIC_TT_NIL:
-      emit_n(pic, cxt, OP_PUSHNIL);
-      return;
-    case PIC_TT_CHAR:
-      emit_c(pic, cxt, OP_PUSHCHAR, pic_char(obj));
-      return;
-    default:
-      check_pool_size(pic, cxt);
-      pidx = (int)cxt->plen++;
-      cxt->pool[pidx] = obj;
-      emit_i(pic, cxt, OP_PUSHCONST, pidx);
-      return;
-    }
+  else if (sym == pic->uBEGIN) {
+    codegen_begin(pic, cxt, obj, tailpos);
   }
-  else if (sym == pic->sCONS) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    emit_n(pic, cxt, OP_CONS);
-    return;
+  else if (sym == pic->uQUOTE) {
+    codegen_quote(pic, cxt, obj, tailpos);
   }
-  else if (sym == pic->sCAR) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_CAR);
-    return;
+  else if (sym == pic->sCALL) {
+    codegen_call(pic, cxt, obj, tailpos);
   }
-  else if (sym == pic->sCDR) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_CDR);
-    return;
+  else {
+    pic_errorf(pic, "codegen: unknown AST type ~s", obj);
   }
-  else if (sym == pic->sNILP) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_NILP);
-    return;
-  }
-  else if (sym == pic->sSYMBOLP) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_SYMBOLP);
-    return;
-  }
-  else if (sym == pic->sPAIRP) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_PAIRP);
-    return;
-  }
-  else if (sym == pic->sADD) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    emit_n(pic, cxt, OP_ADD);
-    return;
-  }
-  else if (sym == pic->sSUB) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    emit_n(pic, cxt, OP_SUB);
-    return;
-  }
-  else if (sym == pic->sMUL) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    emit_n(pic, cxt, OP_MUL);
-    return;
-  }
-  else if (sym == pic->sDIV) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    emit_n(pic, cxt, OP_DIV);
-    return;
-  }
-  else if (sym == pic->sMINUS) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_MINUS);
-    return;
-  }
-  else if (sym == pic->sEQ) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    emit_n(pic, cxt, OP_EQ);
-    return;
-  }
-  else if (sym == pic->sLT) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    emit_n(pic, cxt, OP_LT);
-    return;
-  }
-  else if (sym == pic->sLE) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    emit_n(pic, cxt, OP_LE);
-    return;
-  }
-  else if (sym == pic->sGT) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_LT);
-    return;
-  }
-  else if (sym == pic->sGE) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_LE);
-    return;
-  }
-  else if (sym == pic->sNOT) {
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    emit_n(pic, cxt, OP_NOT);
-    return;
-  }
-  else if (sym == pic->sCALL || sym == pic->sTAILCALL) {
-    int len = (int)pic_length(pic, obj);
-    pic_value elt, it;
-
-    pic_for_each (elt, pic_cdr(pic, obj), it) {
-      codegen(pic, cxt, elt);
-    }
-    emit_i(pic, cxt, (sym == pic->sCALL ? OP_CALL : OP_TAILCALL), len - 1);
-    return;
-  }
-  else if (sym == pic->sCALL_WITH_VALUES || sym == pic->sTAILCALL_WITH_VALUES) {
-    /* stack consumer at first */
-    codegen(pic, cxt, pic_list_ref(pic, obj, 2));
-    codegen(pic, cxt, pic_list_ref(pic, obj, 1));
-    /* call producer */
-    emit_i(pic, cxt, OP_CALL, 1);
-    /* call consumer */
-    emit_i(pic, cxt, (sym == pic->sCALL_WITH_VALUES ? OP_CALL : OP_TAILCALL), -1);
-    return;
-  }
-  else if (sym == pic->sRETURN) {
-    int len = (int)pic_length(pic, obj);
-    pic_value elt, it;
-
-    pic_for_each (elt, pic_cdr(pic, obj), it) {
-      codegen(pic, cxt, elt);
-    }
-    emit_i(pic, cxt, OP_RET, len - 1);
-    return;
-  }
-  pic_errorf(pic, "codegen: unknown AST type ~s", obj);
 }
 
 struct pic_irep *
@@ -1349,7 +1039,7 @@ pic_codegen(pic_state *pic, pic_value obj)
 
   codegen_context_init(pic, cxt, NULL, NULL, empty, empty, empty);
 
-  codegen(pic, cxt, obj);
+  codegen(pic, cxt, obj, true);
 
   return codegen_context_destroy(pic, cxt);
 }
diff --git a/extlib/benz/gc.c b/extlib/benz/gc.c
index b441d786..d9bda339 100644
--- a/extlib/benz/gc.c
+++ b/extlib/benz/gc.c
@@ -521,26 +521,14 @@ gc_mark(pic_state *pic, pic_value v)
 static void
 gc_mark_global_symbols(pic_state *pic)
 {
-  M(sDEFINE); M(sLAMBDA); M(sIF); M(sBEGIN); M(sQUOTE); M(sSETBANG);
-  M(sQUASIQUOTE); M(sUNQUOTE); M(sUNQUOTE_SPLICING);
-  M(sSYNTAX_QUOTE); M(sSYNTAX_QUASIQUOTE); M(sSYNTAX_UNQUOTE);
-  M(sSYNTAX_UNQUOTE_SPLICING);
-  M(sDEFINE_MACRO); M(sIMPORT); M(sEXPORT);
-  M(sDEFINE_LIBRARY);
-  M(sCOND_EXPAND); M(sAND); M(sOR); M(sELSE); M(sLIBRARY);
-  M(sONLY); M(sRENAME); M(sPREFIX); M(sEXCEPT);
-  M(sCONS); M(sCAR); M(sCDR); M(sNILP);
-  M(sSYMBOLP); M(sPAIRP);
-  M(sADD); M(sSUB); M(sMUL); M(sDIV); M(sMINUS);
-  M(sEQ); M(sLT); M(sLE); M(sGT); M(sGE); M(sNOT);
+  M(sQUOTE); M(sQUASIQUOTE); M(sUNQUOTE); M(sUNQUOTE_SPLICING);
+  M(sSYNTAX_QUOTE); M(sSYNTAX_QUASIQUOTE); M(sSYNTAX_UNQUOTE); M(sSYNTAX_UNQUOTE_SPLICING);
+  M(sDEFINE_LIBRARY); M(sIMPORT); M(sEXPORT); M(sCOND_EXPAND);
   M(sREAD); M(sFILE);
-  M(sCALL); M(sTAILCALL); M(sCALL_WITH_VALUES); M(sTAILCALL_WITH_VALUES);
-  M(sGREF); M(sLREF); M(sCREF); M(sRETURN);
+  M(sCALL); M(sGREF); M(sLREF); M(sCREF);
 
-  M(uDEFINE); M(uLAMBDA); M(uIF); M(uBEGIN); M(uQUOTE); M(uSETBANG);
-  M(uDEFINE_MACRO); M(uIMPORT); M(uEXPORT);
-  M(uDEFINE_LIBRARY);
-  M(uCOND_EXPAND);
+  M(uDEFINE); M(uLAMBDA); M(uIF); M(uBEGIN); M(uQUOTE); M(uSETBANG); M(uDEFINE_MACRO);
+  M(uDEFINE_LIBRARY); M(uIMPORT); M(uEXPORT); M(uCOND_EXPAND);
   M(uCONS); M(uCAR); M(uCDR); M(uNILP);
   M(uSYMBOLP); M(uPAIRP);
   M(uADD); M(uSUB); M(uMUL); M(uDIV);
diff --git a/extlib/benz/include/picrin.h b/extlib/benz/include/picrin.h
index 7479ab60..a52fad61 100644
--- a/extlib/benz/include/picrin.h
+++ b/extlib/benz/include/picrin.h
@@ -95,31 +95,16 @@ struct pic_state {
 
   struct pic_lib *lib, *prev_lib;
 
-  pic_sym *sDEFINE, *sLAMBDA, *sIF, *sBEGIN, *sQUOTE, *sSETBANG;
-  pic_sym *sQUASIQUOTE, *sUNQUOTE, *sUNQUOTE_SPLICING;
-  pic_sym *sSYNTAX_QUOTE, *sSYNTAX_QUASIQUOTE, *sSYNTAX_UNQUOTE;
-  pic_sym *sSYNTAX_UNQUOTE_SPLICING;
-  pic_sym *sDEFINE_MACRO, *sIMPORT, *sEXPORT;
-  pic_sym *sDEFINE_LIBRARY;
-  pic_sym *sCOND_EXPAND, *sAND, *sOR, *sELSE, *sLIBRARY;
-  pic_sym *sONLY, *sRENAME, *sPREFIX, *sEXCEPT;
-  pic_sym *sCONS, *sCAR, *sCDR, *sNILP;
-  pic_sym *sSYMBOLP, *sPAIRP;
-  pic_sym *sADD, *sSUB, *sMUL, *sDIV, *sMINUS;
-  pic_sym *sEQ, *sLT, *sLE, *sGT, *sGE, *sNOT;
+  pic_sym *sQUOTE, *sQUASIQUOTE, *sUNQUOTE, *sUNQUOTE_SPLICING;
+  pic_sym *sSYNTAX_QUOTE, *sSYNTAX_QUASIQUOTE, *sSYNTAX_UNQUOTE, *sSYNTAX_UNQUOTE_SPLICING;
+  pic_sym *sDEFINE_LIBRARY, *sIMPORT, *sEXPORT, *sCOND_EXPAND;
+  pic_sym *sGREF, *sCREF, *sLREF, *sCALL;
   pic_sym *sREAD, *sFILE;
-  pic_sym *sGREF, *sCREF, *sLREF;
-  pic_sym *sCALL, *sTAILCALL, *sRETURN;
-  pic_sym *sCALL_WITH_VALUES, *sTAILCALL_WITH_VALUES;
 
-  pic_sym *uDEFINE, *uLAMBDA, *uIF, *uBEGIN, *uQUOTE, *uSETBANG;
-  pic_sym *uDEFINE_MACRO, *uIMPORT, *uEXPORT;
-  pic_sym *uDEFINE_LIBRARY;
-  pic_sym *uCOND_EXPAND;
-  pic_sym *uCONS, *uCAR, *uCDR, *uNILP;
-  pic_sym *uSYMBOLP, *uPAIRP;
-  pic_sym *uADD, *uSUB, *uMUL, *uDIV;
-  pic_sym *uEQ, *uLT, *uLE, *uGT, *uGE, *uNOT;
+  pic_sym *uDEFINE, *uLAMBDA, *uIF, *uBEGIN, *uQUOTE, *uSETBANG, *uDEFINE_MACRO;
+  pic_sym *uDEFINE_LIBRARY, *uIMPORT, *uEXPORT, *uCOND_EXPAND;
+  pic_sym *uCONS, *uCAR, *uCDR, *uNILP, *uSYMBOLP, *uPAIRP;
+  pic_sym *uADD, *uSUB, *uMUL, *uDIV, *uEQ, *uLT, *uLE, *uGT, *uGE, *uNOT;
   pic_sym *uVALUES, *uCALL_WITH_VALUES;
 
   struct pic_lib *PICRIN_BASE;
diff --git a/extlib/benz/include/picrin/config.h b/extlib/benz/include/picrin/config.h
index 30c89e2d..5c284de1 100644
--- a/extlib/benz/include/picrin/config.h
+++ b/extlib/benz/include/picrin/config.h
@@ -128,7 +128,7 @@
 #endif
 
 #ifndef PIC_STACK_SIZE
-# define PIC_STACK_SIZE 1024
+# define PIC_STACK_SIZE 2048
 #endif
 
 #ifndef PIC_RESCUE_SIZE
diff --git a/extlib/benz/state.c b/extlib/benz/state.c
index 9f5cb702..51788c6f 100644
--- a/extlib/benz/state.c
+++ b/extlib/benz/state.c
@@ -284,11 +284,6 @@ pic_open(pic_allocf allocf, void *userdata)
 
 #define S(slot,name) pic->slot = pic_intern_cstr(pic, name)
 
-  S(sDEFINE, "define");
-  S(sLAMBDA, "lambda");
-  S(sIF, "if");
-  S(sBEGIN, "begin");
-  S(sSETBANG, "set!");
   S(sQUOTE, "quote");
   S(sQUASIQUOTE, "quasiquote");
   S(sUNQUOTE, "unquote");
@@ -297,46 +292,16 @@ pic_open(pic_allocf allocf, void *userdata)
   S(sSYNTAX_QUASIQUOTE, "syntax-quasiquote");
   S(sSYNTAX_UNQUOTE, "syntax-unquote");
   S(sSYNTAX_UNQUOTE_SPLICING, "syntax-unquote-splicing");
-  S(sDEFINE_MACRO, "define-macro");
   S(sIMPORT, "import");
   S(sEXPORT, "export");
   S(sDEFINE_LIBRARY, "define-library");
   S(sCOND_EXPAND, "cond-expand");
-  S(sAND, "and");
-  S(sOR, "or");
-  S(sELSE, "else");
-  S(sLIBRARY, "library");
-  S(sONLY, "only");
-  S(sRENAME, "rename");
-  S(sPREFIX, "prefix");
-  S(sEXCEPT, "except");
-  S(sCONS, "cons");
-  S(sCAR, "car");
-  S(sCDR, "cdr");
-  S(sNILP, "null?");
-  S(sSYMBOLP, "symbol?");
-  S(sPAIRP, "pair?");
-  S(sADD, "+");
-  S(sSUB, "-");
-  S(sMUL, "*");
-  S(sDIV, "/");
-  S(sMINUS, "minus");
-  S(sEQ, "=");
-  S(sLT, "<");
-  S(sLE, "<=");
-  S(sGT, ">");
-  S(sGE, ">=");
-  S(sNOT, "not");
   S(sREAD, "read");
   S(sFILE, "file");
   S(sCALL, "call");
-  S(sTAILCALL, "tail-call");
   S(sGREF, "gref");
   S(sLREF, "lref");
   S(sCREF, "cref");
-  S(sRETURN, "return");
-  S(sCALL_WITH_VALUES, "call-with-values");
-  S(sTAILCALL_WITH_VALUES, "tailcall-with-values");
 
   pic_gc_arena_restore(pic, ai);
 
diff --git a/extlib/benz/symbol.c b/extlib/benz/symbol.c
index 772ecf96..b31f7962 100644
--- a/extlib/benz/symbol.c
+++ b/extlib/benz/symbol.c
@@ -32,7 +32,7 @@ pic_intern_cstr(pic_state *pic, const char *cstr)
   strcpy(copy, cstr);
   kh_key(h, it) = copy;
 
-  kh_val(h, it) = pic->sDEFINE; /* insert dummy */
+  kh_val(h, it) = pic->sQUOTE; /* insert dummy */
 
   sym = (pic_sym *)pic_obj_alloc(pic, sizeof(pic_sym), PIC_TT_SYMBOL);
   sym->cstr = copy;
diff --git a/extlib/benz/vm.c b/extlib/benz/vm.c
index 0ccec5ba..58a7acf9 100644
--- a/extlib/benz/vm.c
+++ b/extlib/benz/vm.c
@@ -713,6 +713,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
       pic_value v;
 
       v = pic_false_p(POP()) ? pic_true_value() : pic_false_value();
+      (void)POP();
       PUSH(v);
       NEXT;
     }
@@ -876,6 +877,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
       pic_value a, b;
       pic_gc_protect(pic, b = POP());
       pic_gc_protect(pic, a = POP());
+      (void)POP();
       PUSH(pic_cons(pic, a, b));
       pic_gc_arena_restore(pic, ai);
       NEXT;
@@ -883,32 +885,35 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
     CASE(OP_CAR) {
       pic_value p;
       p = POP();
+      (void)POP();
       PUSH(pic_car(pic, p));
       NEXT;
     }
     CASE(OP_CDR) {
       pic_value p;
       p = POP();
+      (void)POP();
       PUSH(pic_cdr(pic, p));
       NEXT;
     }
     CASE(OP_NILP) {
       pic_value p;
       p = POP();
+      (void)POP();
       PUSH(pic_bool_value(pic_nil_p(p)));
       NEXT;
     }
-
     CASE(OP_SYMBOLP) {
       pic_value p;
       p = POP();
+      (void)POP();
       PUSH(pic_bool_value(pic_sym_p(p)));
       NEXT;
     }
-
     CASE(OP_PAIRP) {
       pic_value p;
       p = POP();
+      (void)POP();
       PUSH(pic_bool_value(pic_pair_p(p)));
       NEXT;
     }
@@ -918,6 +923,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
       pic_value a, b;						\
       b = POP();						\
       a = POP();						\
+      (void)POP();                                              \
       if (pic_int_p(a) && pic_int_p(b)) {			\
 	double f = (double)pic_int(a) op (double)pic_int(b);	\
 	if (INT_MIN <= f && f <= INT_MAX && (guard)) {		\
@@ -947,6 +953,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
       pic_value a, b;						\
       b = POP();						\
       a = POP();						\
+      (void)POP();                                              \
       if (pic_int_p(a) && pic_int_p(b)) {			\
         PUSH(pic_int_value(pic_int(a) op pic_int(b)));          \
       }								\
@@ -971,6 +978,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
     CASE(OP_MINUS) {
       pic_value n;
       n = POP();
+      (void)POP();
       if (pic_int_p(n)) {
 	PUSH(pic_int_value(-pic_int(n)));
       }
@@ -990,6 +998,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
       pic_value a, b;						\
       b = POP();						\
       a = POP();						\
+      (void)POP();                                              \
       if (pic_int_p(a) && pic_int_p(b)) {			\
 	PUSH(pic_bool_value(pic_int(a) op pic_int(b)));		\
       }								\
@@ -1013,6 +1022,7 @@ pic_apply(pic_state *pic, struct pic_proc *proc, pic_value args)
       pic_value a, b;						\
       b = POP();						\
       a = POP();						\
+      (void)POP();                                              \
       if (pic_int_p(a) && pic_int_p(b)) {			\
 	PUSH(pic_bool_value(pic_int(a) op pic_int(b)));		\
       }								\