23 files changed, 175 insertions, 155 deletions

diff --git a/include/mruby.h b/include/mruby.h
index 6d884b146..148addf36 100644
--- a/include/mruby.h
+++ b/include/mruby.h
@@ -89,6 +89,7 @@
 #include <mruby/common.h>
 #include <mruby/value.h>
 #include <mruby/gc.h>
+#include <mruby/presym.h>
 #include <mruby/version.h>
 
 #ifndef MRB_WITHOUT_FLOAT
diff --git a/include/mruby/hash.h b/include/mruby/hash.h
index 86fbe329d..7dab4a85c 100644
--- a/include/mruby/hash.h
+++ b/include/mruby/hash.h
@@ -201,7 +201,7 @@ MRB_API void mrb_hash_merge(mrb_state *mrb, mrb_value hash1, mrb_value hash2);
 /* RHASH_TBL allocates st_table if not available. */
 #define RHASH(obj)   ((struct RHash*)(mrb_ptr(obj)))
 #define RHASH_TBL(h)          (RHASH(h)->ht)
-#define RHASH_IFNONE(h)       mrb_iv_get(mrb, (h), mrb_intern_lit(mrb, "ifnone"))
+#define RHASH_IFNONE(h)       mrb_iv_get(mrb, (h), MRB_SYM(ifnone))
 #define RHASH_PROCDEFAULT(h)  RHASH_IFNONE(h)
 
 #define MRB_HASH_DEFAULT      1
diff --git a/include/mruby/presym.h b/include/mruby/presym.h
new file mode 100644
index 000000000..38e733f25
--- /dev/null
+++ b/include/mruby/presym.h
@@ -0,0 +1,19 @@
+/**
+** @file mruby/presym.h - Preallocated Symbols
+**
+** See Copyright Notice in mruby.h
+*/
+
+#ifndef MRUBY_PRESYM_H
+#define MRUBY_PRESYM_H
+
+#undef MRB_PRESYM_MAX
+#define MRB_PRESYM_CSYM(sym, num) MRB_PRESYM__##sym = (num<<1),
+#define MRB_PRESYM_SYM(sym, num)
+
+enum mruby_presym {
+#include <../build/presym.inc>
+};
+
+#define MRB_SYM(sym) MRB_PRESYM__##sym
+#endif  /* MRUBY_PRESYM_H */
diff --git a/mrbgems/mruby-bin-mirb/tools/mirb/mirb.c b/mrbgems/mruby-bin-mirb/tools/mirb/mirb.c
index 51ba3fd78..19d0bfc06 100644
--- a/mrbgems/mruby-bin-mirb/tools/mirb/mirb.c
+++ b/mrbgems/mruby-bin-mirb/tools/mirb/mirb.c
@@ -672,7 +672,7 @@ main(int argc, char **argv)
         }
         else {
           /* no */
-          if (!mrb_respond_to(mrb, result, mrb_intern_lit(mrb, "inspect"))){
+          if (!mrb_respond_to(mrb, result, MRB_SYM(inspect))){
             result = mrb_any_to_s(mrb, result);
           }
           p(mrb, result, 1);
diff --git a/mrbgems/mruby-compiler/core/codegen.c b/mrbgems/mruby-compiler/core/codegen.c
index c64ffc473..c0d130182 100644
--- a/mrbgems/mruby-compiler/core/codegen.c
+++ b/mrbgems/mruby-compiler/core/codegen.c
@@ -737,7 +737,7 @@ for_body(codegen_scope *s, node *tree)
   genop_2(s, OP_BLOCK, cursp(), s->irep->rlen-1);
   push();pop(); /* space for a block */
   pop();
-  idx = new_sym(s, mrb_intern_lit(s->mrb, "each"));
+  idx = new_sym(s, MRB_SYM(each));
   genop_3(s, OP_SENDB, cursp(), idx, 0);
 }
 
@@ -1489,14 +1489,14 @@ codegen(codegen_scope *s, node *tree, int val)
               gen_move(s, cursp(), exc, 0);
               push_n(2); pop_n(2); /* space for one arg and a block */
               pop();
-              genop_3(s, OP_SEND, cursp(), new_sym(s, mrb_intern_lit(s->mrb, "__case_eqq")), 1);
+              genop_3(s, OP_SEND, cursp(), new_sym(s, MRB_SYM(__case_eqq)), 1);
             }
             else {
               if (n4) {
                 codegen(s, n4->car, VAL);
               }
               else {
-                genop_2(s, OP_GETCONST, cursp(), new_sym(s, mrb_intern_lit(s->mrb, "StandardError")));
+                genop_2(s, OP_GETCONST, cursp(), new_sym(s, MRB_SYM(StandardError)));
                 push();
               }
               pop();
@@ -1739,7 +1739,7 @@ codegen(codegen_scope *s, node *tree, int val)
             gen_move(s, cursp(), head, 0);
             push(); push(); pop(); pop(); pop();
             if (nint(n->car->car) == NODE_SPLAT) {
-              genop_3(s, OP_SEND, cursp(), new_sym(s, mrb_intern_lit(s->mrb, "__case_eqq")), 1);
+              genop_3(s, OP_SEND, cursp(), new_sym(s, MRB_SYM(__case_eqq)), 1);
             }
             else {
               genop_3(s, OP_SEND, cursp(), new_sym(s, mrb_intern_lit(s->mrb, "===")), 1);
@@ -2266,7 +2266,7 @@ codegen(codegen_scope *s, node *tree, int val)
       pop_n(n+1);
       genop_2S(s, OP_BLKPUSH, cursp(), (ainfo<<4)|(lv & 0xf));
       if (sendv) n = CALL_MAXARGS;
-      genop_3(s, OP_SEND, cursp(), new_sym(s, mrb_intern_lit(s->mrb, "call")), n);
+      genop_3(s, OP_SEND, cursp(), new_sym(s, MRB_SYM(call)), n);
       if (val) push();
     }
     break;
@@ -2618,7 +2618,7 @@ codegen(codegen_scope *s, node *tree, int val)
     {
       node *n;
       int ai = mrb_gc_arena_save(s->mrb);
-      int sym = new_sym(s, mrb_intern_lit(s->mrb, "Kernel"));
+      int sym = new_sym(s, MRB_SYM(Kernel));
 
       genop_1(s, OP_LOADSELF, cursp());
       push();
@@ -2698,7 +2698,7 @@ codegen(codegen_scope *s, node *tree, int val)
       }
       push(); /* space for a block */
       pop_n(argc+2);
-      sym = new_sym(s, mrb_intern_lit(s->mrb, "compile"));
+      sym = new_sym(s, MRB_SYM(compile));
       genop_3(s, OP_SEND, cursp(), sym, argc);
       mrb_gc_arena_restore(s->mrb, ai);
       push();
@@ -2752,7 +2752,7 @@ codegen(codegen_scope *s, node *tree, int val)
       }
       push(); /* space for a block */
       pop_n(argc+2);
-      sym = new_sym(s, mrb_intern_lit(s->mrb, "compile"));
+      sym = new_sym(s, MRB_SYM(compile));
       genop_3(s, OP_SEND, cursp(), sym, argc);
       mrb_gc_arena_restore(s->mrb, ai);
       push();
diff --git a/mrbgems/mruby-compiler/core/parse.y b/mrbgems/mruby-compiler/core/parse.y
index 9de45a536..393d6b098 100644
--- a/mrbgems/mruby-compiler/core/parse.y
+++ b/mrbgems/mruby-compiler/core/parse.y
@@ -311,14 +311,14 @@ static void
 local_add_blk(parser_state *p, mrb_sym blk)
 {
   /* allocate register for block */
-  local_add_f(p, blk ? blk : mrb_intern_lit(p->mrb, "&"));
+  local_add_f(p, blk ? blk : intern_lit("&"));
 }
 
 static void
 local_add_kw(parser_state *p, mrb_sym kwd)
 {
   /* allocate register for keywords hash */
-  local_add_f(p, kwd ? kwd : mrb_intern_lit(p->mrb, "**"));
+  local_add_f(p, kwd ? kwd : intern_lit("**"));
 }
 
 static node*
@@ -932,13 +932,13 @@ new_op_asgn(parser_state *p, node *a, mrb_sym op, node *b)
 static node*
 new_imaginary(parser_state *p, node *imaginary)
 {
-  return new_call(p, new_const(p, intern_lit("Kernel")), intern_lit("Complex"), list1(list2(list3((node*)NODE_INT, (node*)strdup("0"), nint(10)), imaginary)), 1);
+  return new_call(p, new_const(p, MRB_SYM(Kernel)), MRB_SYM(Complex), list1(list2(list3((node*)NODE_INT, (node*)strdup("0"), nint(10)), imaginary)), 1);
 }
 
 static node*
 new_rational(parser_state *p, node *rational)
 {
-  return new_call(p, new_const(p, intern_lit("Kernel")), intern_lit("Rational"), list1(list1(rational)), 1);
+  return new_call(p, new_const(p, MRB_SYM(Kernel)), MRB_SYM(Rational), list1(list1(rational)), 1);
 }
 
 /* (:int . i) */
@@ -3010,11 +3010,11 @@ method_call     : operation paren_args
                     }
                 | primary_value call_op paren_args
                     {
-                      $$ = new_call(p, $1, intern_lit("call"), $3, $2);
+                      $$ = new_call(p, $1, MRB_SYM(call), $3, $2);
                     }
                 | primary_value tCOLON2 paren_args
                     {
-                      $$ = new_call(p, $1, intern_lit("call"), $3, tCOLON2);
+                      $$ = new_call(p, $1, MRB_SYM(call), $3, tCOLON2);
                     }
                 | keyword_super paren_args
                     {
@@ -3580,7 +3580,7 @@ f_args          : f_arg ',' f_optarg ',' f_rest_arg opt_args_tail
                     }
                 | /* none */
                     {
-                      local_add_f(p, mrb_intern_lit(p->mrb, "&"));
+                      local_add_f(p, intern_lit("&"));
                       $$ = new_args(p, 0, 0, 0, 0, 0);
                     }
                 ;
@@ -3704,7 +3704,7 @@ f_rest_arg      : restarg_mark tIDENTIFIER
                     }
                 | restarg_mark
                     {
-                      local_add_f(p, mrb_intern_lit(p->mrb, "*"));
+                      local_add_f(p, intern_lit("*"));
                       $$ = -1;
                     }
                 ;
diff --git a/mrbgems/mruby-method/src/method.c b/mrbgems/mruby-method/src/method.c
index 111b031b9..502494dd3 100644
--- a/mrbgems/mruby-method/src/method.c
+++ b/mrbgems/mruby-method/src/method.c
@@ -29,24 +29,24 @@ static mrb_value
 unbound_method_bind(mrb_state *mrb, mrb_value self)
 {
   struct RObject *me;
-  mrb_value owner = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_owner"));
-  mrb_value name = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_name"));
-  mrb_value proc = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_proc"));
-  mrb_value klass = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_klass"));
+  mrb_value owner = mrb_iv_get(mrb, self, MRB_SYM(_owner));
+  mrb_value name = mrb_iv_get(mrb, self, MRB_SYM(_name));
+  mrb_value proc = mrb_iv_get(mrb, self, MRB_SYM(_proc));
+  mrb_value klass = mrb_iv_get(mrb, self, MRB_SYM(_klass));
   mrb_value recv = mrb_get_arg1(mrb);
 
   bind_check(mrb, recv, owner);
   me = method_object_alloc(mrb, mrb_class_get(mrb, "Method"));
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_owner"), owner);
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_recv"), recv);
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_name"), name);
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_proc"), proc);
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_klass"), klass);
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_owner), owner);
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_recv), recv);
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_name), name);
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_proc), proc);
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_klass), klass);
 
   return mrb_obj_value(me);
 }
 
-#define IV_GET(value, name) mrb_iv_get(mrb, value, mrb_intern_lit(mrb, name))
+#define IV_GET(value, name) mrb_iv_get(mrb, value, name)
 static mrb_value
 method_eql(mrb_state *mrb, mrb_value self)
 {
@@ -61,22 +61,22 @@ method_eql(mrb_state *mrb, mrb_value self)
   if (mrb_class(mrb, self) != mrb_class(mrb, other))
     return mrb_false_value();
 
-  klass = mrb_class_ptr(IV_GET(self, "_klass"));
-  if (klass != mrb_class_ptr(IV_GET(other, "_klass")))
+  klass = mrb_class_ptr(IV_GET(self, MRB_SYM(_klass)));
+  if (klass != mrb_class_ptr(IV_GET(other, MRB_SYM(_klass))))
     return mrb_false_value();
 
-  owner = mrb_class_ptr(IV_GET(self, "_owner"));
-  if (owner != mrb_class_ptr(IV_GET(other, "_owner")))
+  owner = mrb_class_ptr(IV_GET(self, MRB_SYM(_owner)));
+  if (owner != mrb_class_ptr(IV_GET(other, MRB_SYM(_owner))))
     return mrb_false_value();
 
-  receiver = IV_GET(self, "_recv");
-  if (!mrb_obj_equal(mrb, receiver, IV_GET(other, "_recv")))
+  receiver = IV_GET(self, MRB_SYM(_recv));
+  if (!mrb_obj_equal(mrb, receiver, IV_GET(other, MRB_SYM(_recv))))
     return mrb_false_value();
 
-  orig_proc = IV_GET(self, "_proc");
-  other_proc = IV_GET(other, "_proc");
+  orig_proc = IV_GET(self, MRB_SYM(_proc));
+  other_proc = IV_GET(other, MRB_SYM(_proc));
   if (mrb_nil_p(orig_proc) && mrb_nil_p(other_proc)) {
-    if (mrb_symbol(IV_GET(self, "_name")) == mrb_symbol(IV_GET(other, "_name")))
+    if (mrb_symbol(IV_GET(self, MRB_SYM(_name))) == mrb_symbol(IV_GET(other, MRB_SYM(_name))))
       return mrb_true_value();
     else
       return mrb_false_value();
@@ -118,7 +118,7 @@ mcall(mrb_state *mrb, mrb_value recv, mrb_value proc, mrb_value name, struct RCl
   if (mrb_nil_p(proc)) {
     mrb_value missing_argv = mrb_ary_new_from_values(mrb, argc, argv);
     mrb_ary_unshift(mrb, missing_argv, name);
-    ret = mrb_funcall_argv(mrb, recv, mrb_intern_lit(mrb, "method_missing"), argc + 1, RARRAY_PTR(missing_argv));
+    ret = mrb_funcall_argv(mrb, recv, MRB_SYM(method_missing), argc + 1, RARRAY_PTR(missing_argv));
   }
   else if (!mrb_nil_p(block)) {
     /*
@@ -137,10 +137,10 @@ mcall(mrb_state *mrb, mrb_value recv, mrb_value proc, mrb_value name, struct RCl
 static mrb_value
 method_call(mrb_state *mrb, mrb_value self)
 {
-  mrb_value proc = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_proc"));
-  mrb_value name = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_name"));
-  mrb_value recv = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_recv"));
-  struct RClass *owner = mrb_class_ptr(mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_owner")));
+  mrb_value proc = mrb_iv_get(mrb, self, MRB_SYM(_proc));
+  mrb_value name = mrb_iv_get(mrb, self, MRB_SYM(_name));
+  mrb_value recv = mrb_iv_get(mrb, self, MRB_SYM(_recv));
+  struct RClass *owner = mrb_class_ptr(mrb_iv_get(mrb, self, MRB_SYM(_owner)));
   mrb_int argc;
   mrb_value *argv, block;
 
@@ -151,10 +151,10 @@ method_call(mrb_state *mrb, mrb_value self)
 static mrb_value
 method_bcall(mrb_state *mrb, mrb_value self)
 {
-  mrb_value proc = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_proc"));
-  mrb_value name = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_name"));
-  mrb_value recv = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_recv"));
-  mrb_value owner = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_owner"));
+  mrb_value proc = mrb_iv_get(mrb, self, MRB_SYM(_proc));
+  mrb_value name = mrb_iv_get(mrb, self, MRB_SYM(_name));
+  mrb_value recv = mrb_iv_get(mrb, self, MRB_SYM(_recv));
+  mrb_value owner = mrb_iv_get(mrb, self, MRB_SYM(_owner));
   mrb_int argc;
   mrb_value *argv, block;
 
@@ -167,17 +167,17 @@ static mrb_value
 method_unbind(mrb_state *mrb, mrb_value self)
 {
   struct RObject *ume;
-  mrb_value owner = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_owner"));
-  mrb_value name = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_name"));
-  mrb_value proc = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_proc"));
-  mrb_value klass = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_klass"));
+  mrb_value owner = mrb_iv_get(mrb, self, MRB_SYM(_owner));
+  mrb_value name = mrb_iv_get(mrb, self, MRB_SYM(_name));
+  mrb_value proc = mrb_iv_get(mrb, self, MRB_SYM(_proc));
+  mrb_value klass = mrb_iv_get(mrb, self, MRB_SYM(_klass));
 
   ume = method_object_alloc(mrb, mrb_class_get(mrb, "UnboundMethod"));
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_owner"), owner);
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_recv"), mrb_nil_value());
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_name"), name);
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_proc"), proc);
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_klass"), klass);
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_owner), owner);
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_recv), mrb_nil_value());
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_name), name);
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_proc), proc);
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_klass), klass);
 
   return mrb_obj_value(ume);
 }
@@ -196,10 +196,10 @@ method_search_vm(mrb_state *mrb, struct RClass **cp, mrb_sym mid)
 static mrb_value
 method_super_method(mrb_state *mrb, mrb_value self)
 {
-  mrb_value recv = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_recv"));
-  mrb_value klass = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_klass"));
-  mrb_value owner = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_owner"));
-  mrb_value name = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_name"));
+  mrb_value recv = mrb_iv_get(mrb, self, MRB_SYM(_recv));
+  mrb_value klass = mrb_iv_get(mrb, self, MRB_SYM(_klass));
+  mrb_value owner = mrb_iv_get(mrb, self, MRB_SYM(_owner));
+  mrb_value name = mrb_iv_get(mrb, self, MRB_SYM(_name));
   struct RClass *super, *rklass;
   struct RProc *proc;
   struct RObject *me;
@@ -225,11 +225,11 @@ method_super_method(mrb_state *mrb, mrb_value self)
     super = super->c;
 
   me = method_object_alloc(mrb, mrb_obj_class(mrb, self));
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_owner"), mrb_obj_value(super));
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_recv"), recv);
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_name"), name);
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_proc"), mrb_obj_value(proc));
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_klass"), mrb_obj_value(rklass));
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_owner), mrb_obj_value(super));
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_recv), recv);
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_name), name);
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_proc), mrb_obj_value(proc));
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_klass), mrb_obj_value(rklass));
 
   return mrb_obj_value(me);
 }
@@ -237,7 +237,7 @@ method_super_method(mrb_state *mrb, mrb_value self)
 static mrb_value
 method_arity(mrb_state *mrb, mrb_value self)
 {
-  mrb_value proc = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_proc"));
+  mrb_value proc = mrb_iv_get(mrb, self, MRB_SYM(_proc));
   mrb_int arity = mrb_nil_p(proc) ? -1 : mrb_proc_arity(mrb_proc_ptr(proc));
   return mrb_fixnum_value(arity);
 }
@@ -245,7 +245,7 @@ method_arity(mrb_state *mrb, mrb_value self)
 static mrb_value
 method_source_location(mrb_state *mrb, mrb_value self)
 {
-  mrb_value proc = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_proc"));
+  mrb_value proc = mrb_iv_get(mrb, self, MRB_SYM(_proc));
   struct RProc *rproc;
   struct RClass *orig;
   mrb_value ret;
@@ -264,13 +264,13 @@ method_source_location(mrb_state *mrb, mrb_value self)
 static mrb_value
 method_parameters(mrb_state *mrb, mrb_value self)
 {
-  mrb_value proc = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_proc"));
+  mrb_value proc = mrb_iv_get(mrb, self, MRB_SYM(_proc));
   struct RProc *rproc;
   struct RClass *orig;
   mrb_value ret;
 
   if (mrb_nil_p(proc)) {
-    mrb_value rest = mrb_symbol_value(mrb_intern_lit(mrb, "rest"));
+    mrb_value rest = mrb_symbol_value(MRB_SYM(rest));
     mrb_value arest = mrb_ary_new_from_values(mrb, 1, &rest);
     return mrb_ary_new_from_values(mrb, 1, &arest);
   }
@@ -286,9 +286,9 @@ method_parameters(mrb_state *mrb, mrb_value self)
 static mrb_value
 method_to_s(mrb_state *mrb, mrb_value self)
 {
-  mrb_value owner = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_owner"));
-  mrb_value klass = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_klass"));
-  mrb_value name = mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_name"));
+  mrb_value owner = mrb_iv_get(mrb, self, MRB_SYM(_owner));
+  mrb_value klass = mrb_iv_get(mrb, self, MRB_SYM(_klass));
+  mrb_value name = mrb_iv_get(mrb, self, MRB_SYM(_name));
   mrb_value str = mrb_str_new_lit(mrb, "#<");
   struct RClass *rklass;
 
@@ -354,11 +354,11 @@ mrb_kernel_method(mrb_state *mrb, mrb_value self)
   mrb_search_method_owner(mrb, mrb_class(mrb, self), self, name, &owner, &proc, FALSE);
 
   me = method_object_alloc(mrb, mrb_class_get(mrb, "Method"));
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_owner"), mrb_obj_value(owner));
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_recv"), self);
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_name"), mrb_symbol_value(name));
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_proc"), proc ? mrb_obj_value(proc) : mrb_nil_value());
-  mrb_obj_iv_set(mrb, me, mrb_intern_lit(mrb, "_klass"), mrb_obj_value(mrb_class(mrb, self)));
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_owner), mrb_obj_value(owner));
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_recv), self);
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_name), mrb_symbol_value(name));
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_proc), proc ? mrb_obj_value(proc) : mrb_nil_value());
+  mrb_obj_iv_set(mrb, me, MRB_SYM(_klass), mrb_obj_value(mrb_class(mrb, self)));
 
   return mrb_obj_value(me);
 }
@@ -376,11 +376,11 @@ mrb_module_instance_method(mrb_state *mrb, mrb_value self)
   mrb_search_method_owner(mrb, mrb_class_ptr(self), self, name, &owner, &proc, TRUE);
 
   ume = method_object_alloc(mrb, mrb_class_get(mrb, "UnboundMethod"));
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_owner"), mrb_obj_value(owner));
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_recv"), mrb_nil_value());
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_name"), mrb_symbol_value(name));
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_proc"), proc ? mrb_obj_value(proc) : mrb_nil_value());
-  mrb_obj_iv_set(mrb, ume, mrb_intern_lit(mrb, "_klass"), self);
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_owner), mrb_obj_value(owner));
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_recv), mrb_nil_value());
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_name), mrb_symbol_value(name));
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_proc), proc ? mrb_obj_value(proc) : mrb_nil_value());
+  mrb_obj_iv_set(mrb, ume, MRB_SYM(_klass), self);
 
   return mrb_obj_value(ume);
 }
@@ -388,19 +388,19 @@ mrb_module_instance_method(mrb_state *mrb, mrb_value self)
 static mrb_value
 method_owner(mrb_state *mrb, mrb_value self)
 {
-  return mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_owner"));
+  return mrb_iv_get(mrb, self, MRB_SYM(_owner));
 }
 
 static mrb_value
 method_receiver(mrb_state *mrb, mrb_value self)
 {
-  return mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_recv"));
+  return mrb_iv_get(mrb, self, MRB_SYM(_recv));
 }
 
 static mrb_value
 method_name(mrb_state *mrb, mrb_value self)
 {
-  return mrb_iv_get(mrb, self, mrb_intern_lit(mrb, "_name"));
+  return mrb_iv_get(mrb, self, MRB_SYM(_name));
 }
 
 void
diff --git a/mrbgems/mruby-objectspace/src/mruby_objectspace.c b/mrbgems/mruby-objectspace/src/mruby_objectspace.c
index bded3afa8..16edafced 100644
--- a/mrbgems/mruby-objectspace/src/mruby_objectspace.c
+++ b/mrbgems/mruby-objectspace/src/mruby_objectspace.c
@@ -71,8 +71,8 @@ os_count_objects(mrb_state *mrb, mrb_value self)
 
   mrb_objspace_each_objects(mrb, os_count_object_type, &obj_count);
 
-  mrb_hash_set(mrb, hash, mrb_symbol_value(mrb_intern_lit(mrb, "TOTAL")), mrb_fixnum_value(obj_count.total));
-  mrb_hash_set(mrb, hash, mrb_symbol_value(mrb_intern_lit(mrb, "FREE")), mrb_fixnum_value(obj_count.freed));
+  mrb_hash_set(mrb, hash, mrb_symbol_value(MRB_SYM(TOTAL)), mrb_fixnum_value(obj_count.total));
+  mrb_hash_set(mrb, hash, mrb_symbol_value(MRB_SYM(FREE)), mrb_fixnum_value(obj_count.freed));
 
   for (i = MRB_TT_FALSE; i < MRB_TT_MAXDEFINE; i++) {
     mrb_value type;
diff --git a/mrbgems/mruby-random/src/random.c b/mrbgems/mruby-random/src/random.c
index 10c81b946..c3a3f61b4 100644
--- a/mrbgems/mruby-random/src/random.c
+++ b/mrbgems/mruby-random/src/random.c
@@ -144,7 +144,7 @@ random_check(mrb_state *mrb, mrb_value random) {
 static mrb_value
 random_default(mrb_state *mrb) {
   struct RClass *c = mrb_class_get(mrb, "Random");
-  mrb_value d = mrb_const_get(mrb, mrb_obj_value(c), mrb_intern_lit(mrb, "DEFAULT"));
+  mrb_value d = mrb_const_get(mrb, mrb_obj_value(c), MRB_SYM(DEFAULT));
   if (!mrb_obj_is_kind_of(mrb, d, c)) {
     mrb_raise(mrb, E_TYPE_ERROR, "Random::DEFAULT replaced");
   }
@@ -401,7 +401,7 @@ void mrb_mruby_random_gem_init(mrb_state *mrb)
   mrb_define_method(mrb, array, "shuffle!", mrb_ary_shuffle_bang, MRB_ARGS_OPT(1));
   mrb_define_method(mrb, array, "sample", mrb_ary_sample, MRB_ARGS_OPT(2));
 
-  mrb_const_set(mrb, mrb_obj_value(random), mrb_intern_lit(mrb, "DEFAULT"),
+  mrb_const_set(mrb, mrb_obj_value(random), MRB_SYM(DEFAULT),
           mrb_obj_new(mrb, random, 0, NULL));
 }
 
diff --git a/mrbgems/mruby-socket/src/socket.c b/mrbgems/mruby-socket/src/socket.c
index a819dcb29..3916e35b9 100644
--- a/mrbgems/mruby-socket/src/socket.c
+++ b/mrbgems/mruby-socket/src/socket.c
@@ -163,17 +163,17 @@ mrb_addrinfo_getaddrinfo(mrb_state *mrb, mrb_value klass)
     hints.ai_protocol = (int)mrb_fixnum(protocol);
   }
 
-  lastai = mrb_cv_get(mrb, klass, mrb_intern_lit(mrb, "_lastai"));
+  lastai = mrb_cv_get(mrb, klass, MRB_SYM(_lastai));
   if (mrb_cptr_p(lastai)) {
     freeaddrinfo((struct addrinfo*)mrb_cptr(lastai));
-    mrb_cv_set(mrb, klass, mrb_intern_lit(mrb, "_lastai"), mrb_nil_value());
+    mrb_cv_set(mrb, klass, MRB_SYM(_lastai), mrb_nil_value());
   }
 
   error = getaddrinfo(hostname, servname, &hints, &res0);
   if (error) {
     mrb_raisef(mrb, E_SOCKET_ERROR, "getaddrinfo: %s", gai_strerror(error));
   }
-  mrb_cv_set(mrb, klass, mrb_intern_lit(mrb, "_lastai"), mrb_cptr_value(mrb, res0));
+  mrb_cv_set(mrb, klass, MRB_SYM(_lastai), mrb_cptr_value(mrb, res0));
 
   for (res = res0; res != NULL; res = res->ai_next) {
     sa = mrb_str_new(mrb, (char*)res->ai_addr, res->ai_addrlen);
@@ -183,7 +183,7 @@ mrb_addrinfo_getaddrinfo(mrb_state *mrb, mrb_value klass)
   }
 
   freeaddrinfo(res0);
-  mrb_cv_set(mrb, klass, mrb_intern_lit(mrb, "_lastai"), mrb_nil_value());
+  mrb_cv_set(mrb, klass, MRB_SYM(_lastai), mrb_nil_value());
 
   return ary;
 }
@@ -347,7 +347,7 @@ mrb_basicsocket_getsockopt(mrb_state *mrb, mrb_value self)
   optlen = sizeof(opt);
   if (getsockopt(s, (int)level, (int)optname, opt, &optlen) == -1)
     mrb_sys_fail(mrb, "getsockopt");
-  c = mrb_const_get(mrb, mrb_obj_value(mrb_class_get(mrb, "Socket")), mrb_intern_lit(mrb, "Option"));
+  c = mrb_const_get(mrb, mrb_obj_value(mrb_class_get(mrb, "Socket")), MRB_SYM(Option));
   family = socket_family(s);
   data = mrb_str_new(mrb, opt, optlen);
   return mrb_funcall(mrb, c, "new", 4, mrb_fixnum_value(family), mrb_fixnum_value(level), mrb_fixnum_value(optname), data);
@@ -862,7 +862,7 @@ mrb_mruby_socket_gem_init(mrb_state* mrb)
 #endif
 
   ai = mrb_define_class(mrb, "Addrinfo", mrb->object_class);
-  mrb_mod_cv_set(mrb, ai, mrb_intern_lit(mrb, "_lastai"), mrb_nil_value());
+  mrb_mod_cv_set(mrb, ai, MRB_SYM(_lastai), mrb_nil_value());
   mrb_define_class_method(mrb, ai, "getaddrinfo", mrb_addrinfo_getaddrinfo, MRB_ARGS_REQ(2)|MRB_ARGS_OPT(4));
   mrb_define_method(mrb, ai, "getnameinfo", mrb_addrinfo_getnameinfo, MRB_ARGS_OPT(1));
 #ifndef _WIN32
@@ -948,7 +948,7 @@ void
 mrb_mruby_socket_gem_final(mrb_state* mrb)
 {
   mrb_value ai;
-  ai = mrb_mod_cv_get(mrb, mrb_class_get(mrb, "Addrinfo"), mrb_intern_lit(mrb, "_lastai"));
+  ai = mrb_mod_cv_get(mrb, mrb_class_get(mrb, "Addrinfo"), MRB_SYM(_lastai));
   if (mrb_cptr_p(ai)) {
     freeaddrinfo((struct addrinfo*)mrb_cptr(ai));
   }
diff --git a/mrbgems/mruby-struct/src/struct.c b/mrbgems/mruby-struct/src/struct.c
index 7fbf9225f..ee5ef85ae 100644
--- a/mrbgems/mruby-struct/src/struct.c
+++ b/mrbgems/mruby-struct/src/struct.c
@@ -42,7 +42,7 @@ struct_ivar_get(mrb_state *mrb, mrb_value cls, mrb_sym id)
 static mrb_value
 struct_s_members(mrb_state *mrb, struct RClass *klass)
 {
-  mrb_value members = struct_ivar_get(mrb, mrb_obj_value(klass), mrb_intern_lit(mrb, "__members__"));
+  mrb_value members = struct_ivar_get(mrb, mrb_obj_value(klass), MRB_SYM(__members__));
 
   if (mrb_nil_p(members)) {
     mrb_raise(mrb, E_TYPE_ERROR, "uninitialized struct");
@@ -214,7 +214,7 @@ make_struct(mrb_state *mrb, mrb_value name, mrb_value members, struct RClass *kl
   }
   MRB_SET_INSTANCE_TT(c, MRB_TT_ARRAY);
   nstr = mrb_obj_value(c);
-  mrb_iv_set(mrb, nstr, mrb_intern_lit(mrb, "__members__"), members);
+  mrb_iv_set(mrb, nstr, MRB_SYM(__members__), members);
 
   mrb_define_class_method(mrb, c, "new", mrb_instance_new, MRB_ARGS_ANY());
   mrb_define_class_method(mrb, c, "[]", mrb_instance_new, MRB_ARGS_ANY());
@@ -310,7 +310,7 @@ num_members(mrb_state *mrb, struct RClass *klass)
 {
   mrb_value members;
 
-  members = struct_ivar_get(mrb, mrb_obj_value(klass), mrb_intern_lit(mrb, "__members__"));
+  members = struct_ivar_get(mrb, mrb_obj_value(klass), MRB_SYM(__members__));
   if (!mrb_array_p(members)) {
     mrb_raise(mrb, E_TYPE_ERROR, "broken members");
   }
diff --git a/src/array.c b/src/array.c
index c33641264..567ed7d8b 100644
--- a/src/array.c
+++ b/src/array.c
@@ -1312,11 +1312,11 @@ init_ary_each(mrb_state *mrb, struct RClass *ary)
 
   *each_irep = mrb_irep_zero;
   each_irep->syms = (mrb_sym*)mrb_malloc(mrb, sizeof(mrb_sym)*5);
-  each_irep->syms[0] = mrb_intern_lit(mrb, "each");
-  each_irep->syms[1] = mrb_intern_lit(mrb, "to_enum");
+  each_irep->syms[0] = MRB_SYM(each);
+  each_irep->syms[1] = MRB_SYM(to_enum);
   each_irep->syms[2] = mrb_intern_lit(mrb, "[]");
-  each_irep->syms[3] = mrb_intern_lit(mrb, "call");
-  each_irep->syms[4] = mrb_intern_lit(mrb, "length");
+  each_irep->syms[3] = MRB_SYM(call);
+  each_irep->syms[4] = MRB_SYM(length);
   each_irep->slen = 5;
   each_irep->flags = MRB_ISEQ_NO_FREE;
   each_irep->iseq = each_iseq;
@@ -1326,7 +1326,7 @@ init_ary_each(mrb_state *mrb, struct RClass *ary)
   p = mrb_proc_new(mrb, each_irep);
   p->flags |= MRB_PROC_SCOPE | MRB_PROC_STRICT;
   MRB_METHOD_FROM_PROC(m, p);
-  mrb_define_method_raw(mrb, ary, mrb_intern_lit(mrb, "each"), m);
+  mrb_define_method_raw(mrb, ary, MRB_SYM(each), m);
 }
 
 void
diff --git a/src/backtrace.c b/src/backtrace.c
index 591f4ea4b..b614a04be 100644
--- a/src/backtrace.c
+++ b/src/backtrace.c
@@ -114,7 +114,7 @@ mrb_print_backtrace(mrb_state *mrb)
     return;
   }
 
-  backtrace = mrb_obj_iv_get(mrb, mrb->exc, mrb_intern_lit(mrb, "backtrace"));
+  backtrace = mrb_obj_iv_get(mrb, mrb->exc, MRB_SYM(backtrace));
   if (mrb_nil_p(backtrace)) return;
   if (!mrb_array_p(backtrace)) backtrace = mrb_unpack_backtrace(mrb, backtrace);
   print_backtrace(mrb, mrb->exc, backtrace);
@@ -171,7 +171,7 @@ packed_backtrace(mrb_state *mrb)
 void
 mrb_keep_backtrace(mrb_state *mrb, mrb_value exc)
 {
-  mrb_sym sym = mrb_intern_lit(mrb, "backtrace");
+  mrb_sym sym = MRB_SYM(backtrace);
   mrb_value backtrace;
   int ai;
 
@@ -221,7 +221,7 @@ mrb_exc_backtrace(mrb_state *mrb, mrb_value exc)
   mrb_sym attr_name;
   mrb_value backtrace;
 
-  attr_name = mrb_intern_lit(mrb, "backtrace");
+  attr_name = MRB_SYM(backtrace);
   backtrace = mrb_iv_get(mrb, exc, attr_name);
   if (mrb_nil_p(backtrace) || mrb_array_p(backtrace)) {
     return backtrace;
diff --git a/src/class.c b/src/class.c
index fcbdadea8..465577e1a 100644
--- a/src/class.c
+++ b/src/class.c
@@ -58,7 +58,7 @@ void
 mrb_class_name_class(mrb_state *mrb, struct RClass *outer, struct RClass *c, mrb_sym id)
 {
   mrb_value name;
-  mrb_sym nsym = mrb_intern_lit(mrb, "__classname__");
+  mrb_sym nsym = MRB_SYM(__classname__);
 
   if (mrb_obj_iv_defined(mrb, (struct RObject*)c, nsym)) return;
   if (outer == NULL || outer == mrb->object_class) {
@@ -68,7 +68,7 @@ mrb_class_name_class(mrb_state *mrb, struct RClass *outer, struct RClass *c, mrb
     name = mrb_class_path(mrb, outer);
     if (mrb_nil_p(name)) {      /* unnamed outer class */
       if (outer != mrb->object_class && outer != c) {
-        mrb_obj_iv_set_force(mrb, (struct RObject*)c, mrb_intern_lit(mrb, "__outer__"),
+        mrb_obj_iv_set_force(mrb, (struct RObject*)c, MRB_SYM(__outer__),
                              mrb_obj_value(outer));
       }
       return;
@@ -132,7 +132,7 @@ prepare_singleton_class(mrb_state *mrb, struct RBasic *o)
   o->c = sc;
   mrb_field_write_barrier(mrb, (struct RBasic*)o, (struct RBasic*)sc);
   mrb_field_write_barrier(mrb, (struct RBasic*)sc, (struct RBasic*)o);
-  mrb_obj_iv_set(mrb, (struct RObject*)sc, mrb_intern_lit(mrb, "__attached__"), mrb_obj_value(o));
+  mrb_obj_iv_set(mrb, (struct RObject*)sc, MRB_SYM(__attached__), mrb_obj_value(o));
   sc->flags |= o->flags & MRB_FL_OBJ_IS_FROZEN;
 }
 
@@ -302,7 +302,7 @@ mrb_class_inherited(mrb_state *mrb, struct RClass *super, struct RClass *klass)
   super->flags |= MRB_FL_CLASS_IS_INHERITED;
   s = mrb_obj_value(super);
   mrb_mc_clear_by_class(mrb, klass);
-  mid = mrb_intern_lit(mrb, "inherited");
+  mid = MRB_SYM(inherited);
   if (!mrb_func_basic_p(mrb, s, mid, mrb_bob_init)) {
     mrb_value c = mrb_obj_value(klass);
     mrb_funcall_argv(mrb, s, mid, 1, &c);
@@ -1578,7 +1578,7 @@ mrb_instance_new(mrb_state *mrb, mrb_value cv)
 
   mrb_get_args(mrb, "*!&", &argv, &argc, &blk);
   obj = mrb_instance_alloc(mrb, cv);
-  init = mrb_intern_lit(mrb, "initialize");
+  init = MRB_SYM(initialize);
   if (!mrb_func_basic_p(mrb, obj, init, mrb_bob_init)) {
     mrb_funcall_with_block(mrb, obj, init, argc, argv, blk);
   }
@@ -1592,7 +1592,7 @@ mrb_obj_new(mrb_state *mrb, struct RClass *c, mrb_int argc, const mrb_value *arg
   mrb_sym mid;
 
   obj = mrb_instance_alloc(mrb, mrb_obj_value(c));
-  mid = mrb_intern_lit(mrb, "initialize");
+  mid = MRB_SYM(initialize);
   if (!mrb_func_basic_p(mrb, obj, mid, mrb_bob_init)) {
     mrb_funcall_argv(mrb, obj, mid, argc, argv);
   }
@@ -1624,7 +1624,7 @@ mrb_class_new_class(mrb_state *mrb, mrb_value cv)
     super = mrb_obj_value(mrb->object_class);
   }
   new_class = mrb_obj_value(mrb_class_new(mrb, mrb_class_ptr(super)));
-  mid = mrb_intern_lit(mrb, "initialize");
+  mid = MRB_SYM(initialize);
   if (mrb_func_basic_p(mrb, new_class, mid, mrb_class_initialize)) {
     mrb_class_initialize(mrb, new_class);
   }
@@ -1722,7 +1722,7 @@ MRB_API mrb_value
 mrb_class_path(mrb_state *mrb, struct RClass *c)
 {
   mrb_value path;
-  mrb_sym nsym = mrb_intern_lit(mrb, "__classname__");
+  mrb_sym nsym = MRB_SYM(__classname__);
 
   path = mrb_obj_iv_get(mrb, (struct RObject*)c, nsym);
   if (mrb_nil_p(path)) {
@@ -1891,7 +1891,7 @@ mrb_mod_to_s(mrb_state *mrb, mrb_value klass)
 {
 
   if (mrb_sclass_p(klass)) {
-    mrb_value v = mrb_iv_get(mrb, klass, mrb_intern_lit(mrb, "__attached__"));
+    mrb_value v = mrb_iv_get(mrb, klass, MRB_SYM(__attached__));
     mrb_value str = mrb_str_new_lit(mrb, "#<Class:");
 
     if (class_ptr_p(v)) {
@@ -2239,8 +2239,8 @@ init_class_new(mrb_state *mrb, struct RClass *cls)
 
   *new_irep = mrb_irep_zero;
   new_irep->syms = (mrb_sym*)mrb_malloc(mrb, sizeof(mrb_sym)*2);
-  new_irep->syms[0] = mrb_intern_lit(mrb, "allocate");
-  new_irep->syms[1] = mrb_intern_lit(mrb, "initialize");
+  new_irep->syms[0] = MRB_SYM(allocate);
+  new_irep->syms[1] = MRB_SYM(initialize);
   new_irep->slen = 2;
   new_irep->flags = MRB_ISEQ_NO_FREE;
   new_irep->iseq = new_iseq;
@@ -2249,7 +2249,7 @@ init_class_new(mrb_state *mrb, struct RClass *cls)
   new_irep->nlocals = 3;
   p = mrb_proc_new(mrb, new_irep);
   MRB_METHOD_FROM_PROC(m, p);
-  mrb_define_method_raw(mrb, cls, mrb_intern_lit(mrb, "new"), m);
+  mrb_define_method_raw(mrb, cls, MRB_SYM(new), m);
 }
 
 void
@@ -2279,10 +2279,10 @@ mrb_init_class(mrb_state *mrb)
   mrb_define_const(mrb, obj, "Class",       mrb_obj_value(cls));
 
   /* name each classes */
-  mrb_class_name_class(mrb, NULL, bob, mrb_intern_lit(mrb, "BasicObject"));
-  mrb_class_name_class(mrb, NULL, obj, mrb_intern_lit(mrb, "Object")); /* 15.2.1 */
-  mrb_class_name_class(mrb, NULL, mod, mrb_intern_lit(mrb, "Module")); /* 15.2.2 */
-  mrb_class_name_class(mrb, NULL, cls, mrb_intern_lit(mrb, "Class"));  /* 15.2.3 */
+  mrb_class_name_class(mrb, NULL, bob, MRB_SYM(BasicObject));
+  mrb_class_name_class(mrb, NULL, obj, MRB_SYM(Object)); /* 15.2.1 */
+  mrb_class_name_class(mrb, NULL, mod, MRB_SYM(Module)); /* 15.2.2 */
+  mrb_class_name_class(mrb, NULL, cls, MRB_SYM(Class));  /* 15.2.3 */
 
   mrb->proc_class = mrb_define_class(mrb, "Proc", mrb->object_class);  /* 15.2.17 */
   MRB_SET_INSTANCE_TT(mrb->proc_class, MRB_TT_PROC);
diff --git a/src/error.c b/src/error.c
index 5d17209e5..30835e206 100644
--- a/src/error.c
+++ b/src/error.c
@@ -45,7 +45,7 @@ exc_initialize(mrb_state *mrb, mrb_value exc)
   mrb_value mesg;
 
   if (mrb_get_args(mrb, "|o", &mesg) == 1) {
-    mrb_iv_set(mrb, exc, mrb_intern_lit(mrb, "mesg"), mesg);
+    mrb_iv_set(mrb, exc, MRB_SYM(mesg), mesg);
   }
   return exc;
 }
@@ -74,7 +74,7 @@ exc_exception(mrb_state *mrb, mrb_value self)
   if (argc == 0) return self;
   if (mrb_obj_equal(mrb, self, a)) return self;
   exc = mrb_obj_clone(mrb, self);
-  mrb_iv_set(mrb, exc, mrb_intern_lit(mrb, "mesg"), a);
+  mrb_iv_set(mrb, exc, MRB_SYM(mesg), a);
 
   return exc;
 }
@@ -90,7 +90,7 @@ exc_exception(mrb_state *mrb, mrb_value self)
 mrb_value
 exc_to_s(mrb_state *mrb, mrb_value exc)
 {
-  mrb_value mesg = mrb_attr_get(mrb, exc, mrb_intern_lit(mrb, "mesg"));
+  mrb_value mesg = mrb_attr_get(mrb, exc, MRB_SYM(mesg));
   struct RObject *p;
 
   if (!mrb_string_p(mesg)) {
@@ -130,7 +130,7 @@ exc_message(mrb_state *mrb, mrb_value exc)
 mrb_value
 mrb_exc_inspect(mrb_state *mrb, mrb_value exc)
 {
-  mrb_value mesg = mrb_attr_get(mrb, exc, mrb_intern_lit(mrb, "mesg"));
+  mrb_value mesg = mrb_attr_get(mrb, exc, MRB_SYM(mesg));
   mrb_value cname = mrb_mod_to_s(mrb, mrb_obj_value(mrb_obj_class(mrb, exc)));
   mesg = mrb_obj_as_string(mrb, mesg);
   return RSTRING_LEN(mesg) == 0 ? cname : mrb_format(mrb, "%v (%v)", mesg, cname);
@@ -154,7 +154,7 @@ set_backtrace(mrb_state *mrb, mrb_value exc, mrb_value backtrace)
       p++;
     }
   }
-  mrb_iv_set(mrb, exc, mrb_intern_lit(mrb, "backtrace"), backtrace);
+  mrb_iv_set(mrb, exc, MRB_SYM(backtrace), backtrace);
 }
 
 static mrb_value
@@ -474,7 +474,7 @@ mrb_make_exception(mrb_state *mrb, mrb_int argc, const mrb_value *argv)
       n = 1;
 exception_call:
       {
-        mrb_sym exc = mrb_intern_lit(mrb, "exception");
+        mrb_sym exc = MRB_SYM(exception);
         if (mrb_respond_to(mrb, argv[0], exc)) {
           mesg = mrb_funcall_argv(mrb, argv[0], exc, n, argv+1);
         }
diff --git a/src/hash.c b/src/hash.c
index c891e1b22..a9ac79226 100644
--- a/src/hash.c
+++ b/src/hash.c
@@ -683,7 +683,7 @@ mrb_hash_init_copy(mrb_state *mrb, mrb_value self)
   vret = mrb_obj_value(copy);
   ifnone = RHASH_IFNONE(self);
   if (!mrb_nil_p(ifnone)) {
-      mrb_iv_set(mrb, vret, mrb_intern_lit(mrb, "ifnone"), ifnone);
+    mrb_iv_set(mrb, vret, MRB_SYM(ifnone), ifnone);
   }
   return vret;
 }
@@ -729,7 +729,7 @@ mrb_hash_get(mrb_state *mrb, mrb_value hash, mrb_value key)
     return val;
   }
 
-  mid = mrb_intern_lit(mrb, "default");
+  mid = MRB_SYM(default);
   if (mrb_func_basic_p(mrb, hash, mid, mrb_hash_default)) {
     return hash_default(mrb, hash, key);
   }
@@ -824,7 +824,7 @@ mrb_hash_init(mrb_state *mrb, mrb_value hash)
   }
   if (!mrb_nil_p(ifnone)) {
     RHASH(hash)->flags |= MRB_HASH_DEFAULT;
-    mrb_iv_set(mrb, hash, mrb_intern_lit(mrb, "ifnone"), ifnone);
+    mrb_iv_set(mrb, hash, MRB_SYM(ifnone), ifnone);
   }
   return hash;
 }
@@ -933,7 +933,7 @@ mrb_hash_set_default(mrb_state *mrb, mrb_value hash)
   mrb_value ifnone = mrb_get_arg1(mrb);
 
   mrb_hash_modify(mrb, hash);
-  mrb_iv_set(mrb, hash, mrb_intern_lit(mrb, "ifnone"), ifnone);
+  mrb_iv_set(mrb, hash, MRB_SYM(ifnone), ifnone);
   RHASH(hash)->flags &= ~MRB_HASH_PROC_DEFAULT;
   if (!mrb_nil_p(ifnone)) {
     RHASH(hash)->flags |= MRB_HASH_DEFAULT;
@@ -988,7 +988,7 @@ mrb_hash_set_default_proc(mrb_state *mrb, mrb_value hash)
   mrb_value ifnone = mrb_get_arg1(mrb);
 
   mrb_hash_modify(mrb, hash);
-  mrb_iv_set(mrb, hash, mrb_intern_lit(mrb, "ifnone"), ifnone);
+  mrb_iv_set(mrb, hash, MRB_SYM(ifnone), ifnone);
   if (!mrb_nil_p(ifnone)) {
     RHASH(hash)->flags |= MRB_HASH_PROC_DEFAULT;
     RHASH(hash)->flags |= MRB_HASH_DEFAULT;
diff --git a/src/kernel.c b/src/kernel.c
index 10ed9f88e..e192ed752 100644
--- a/src/kernel.c
+++ b/src/kernel.c
@@ -33,7 +33,7 @@ mrb_func_basic_p(mrb_state *mrb, mrb_value obj, mrb_sym mid, mrb_func_t func)
 static mrb_bool
 mrb_obj_basic_to_s_p(mrb_state *mrb, mrb_value obj)
 {
-  return mrb_func_basic_p(mrb, obj, mrb_intern_lit(mrb, "to_s"), mrb_any_to_s);
+  return mrb_func_basic_p(mrb, obj, MRB_SYM(to_s), mrb_any_to_s);
 }
 
 /* 15.3.1.3.17 */
@@ -240,7 +240,7 @@ mrb_singleton_class_clone(mrb_state *mrb, mrb_value obj)
     clone->super = klass->super;
     if (klass->iv) {
       mrb_iv_copy(mrb, mrb_obj_value(clone), mrb_obj_value(klass));
-      mrb_obj_iv_set(mrb, (struct RObject*)clone, mrb_intern_lit(mrb, "__attached__"), obj);
+      mrb_obj_iv_set(mrb, (struct RObject*)clone, MRB_SYM(__attached__), obj);
     }
     if (klass->mt) {
       clone->mt = kh_copy(mt, mrb, klass->mt);
@@ -294,7 +294,7 @@ init_copy(mrb_state *mrb, mrb_value dest, mrb_value obj)
     case MRB_TT_MODULE:
       copy_class(mrb, dest, obj);
       mrb_iv_copy(mrb, dest, obj);
-      mrb_iv_remove(mrb, dest, mrb_intern_lit(mrb, "__classname__"));
+      mrb_iv_remove(mrb, dest, MRB_SYM(__classname__));
       break;
     case MRB_TT_OBJECT:
     case MRB_TT_SCLASS:
diff --git a/src/print.c b/src/print.c
index a75814d81..6bf7da6a5 100644
--- a/src/print.c
+++ b/src/print.c
@@ -60,11 +60,11 @@ mrb_print_error(mrb_state *mrb)
 MRB_API void
 mrb_show_version(mrb_state *mrb)
 {
-  printstr(mrb_const_get(mrb, mrb_obj_value(mrb->object_class), mrb_intern_lit(mrb, "MRUBY_DESCRIPTION")), stdout);
+  printstr(mrb_const_get(mrb, mrb_obj_value(mrb->object_class), MRB_SYM(MRUBY_DESCRIPTION)), stdout);
 }
 
 MRB_API void
 mrb_show_copyright(mrb_state *mrb)
 {
-  printstr(mrb_const_get(mrb, mrb_obj_value(mrb->object_class), mrb_intern_lit(mrb, "MRUBY_COPYRIGHT")), stdout);
+  printstr(mrb_const_get(mrb, mrb_obj_value(mrb->object_class), MRB_SYM(MRUBY_COPYRIGHT)), stdout);
 }
diff --git a/src/proc.c b/src/proc.c
index c00b09acf..743e9610c 100644
--- a/src/proc.c
+++ b/src/proc.c
@@ -200,7 +200,7 @@ mrb_proc_s_new(mrb_state *mrb, mrb_value proc_class)
   p = (struct RProc *)mrb_obj_alloc(mrb, MRB_TT_PROC, mrb_class_ptr(proc_class));
   mrb_proc_copy(p, mrb_proc_ptr(blk));
   proc = mrb_obj_value(p);
-  mrb_funcall_with_block(mrb, proc, mrb_intern_lit(mrb, "initialize"), 0, NULL, proc);
+  mrb_funcall_with_block(mrb, proc, MRB_SYM(initialize), 0, NULL, proc);
   if (!MRB_PROC_STRICT_P(p) &&
       mrb->c->ci > mrb->c->cibase && MRB_PROC_ENV(p) == mrb->c->ci[-1].env) {
     p->flags |= MRB_PROC_ORPHAN;
@@ -325,7 +325,7 @@ mrb_init_proc(mrb_state *mrb)
   p = mrb_proc_new(mrb, call_irep);
   irep_obj->data = NULL;
   MRB_METHOD_FROM_PROC(m, p);
-  mrb_define_method_raw(mrb, mrb->proc_class, mrb_intern_lit(mrb, "call"), m);
+  mrb_define_method_raw(mrb, mrb->proc_class, MRB_SYM(call), m);
   mrb_define_method_raw(mrb, mrb->proc_class, mrb_intern_lit(mrb, "[]"), m);
 
   mrb_define_class_method(mrb, mrb->kernel_module, "lambda", proc_lambda, MRB_ARGS_NONE()|MRB_ARGS_BLOCK()); /* 15.3.1.2.6  */
diff --git a/src/range.c b/src/range.c
index 0b4e6dbca..868d3d397 100644
--- a/src/range.c
+++ b/src/range.c
@@ -78,7 +78,7 @@ range_ptr_init(mrb_state *mrb, struct RRange *r, mrb_value beg, mrb_value end, m
   if (r) {
     if (RANGE_INITIALIZED_P(r)) {
       /* Ranges are immutable, so that they should be initialized only once. */
-      mrb_name_error(mrb, mrb_intern_lit(mrb, "initialize"), "'initialize' called twice");
+      mrb_name_error(mrb, MRB_SYM(initialize), "'initialize' called twice");
     }
     else {
       range_ptr_alloc_edges(mrb, r);
diff --git a/src/symbol.c b/src/symbol.c
index a78dd5f4c..a09298b23 100644
--- a/src/symbol.c
+++ b/src/symbol.c
@@ -13,6 +13,8 @@
 #include <mruby/class.h>
 
 #undef MRB_PRESYM_MAX
+#undef MRB_PRESYM_CSYM
+#undef MRB_PRESYM_SYM
 #define MRB_PRESYM_CSYM(sym, num) #sym,
 #define MRB_PRESYM_SYM(sym, num) #sym,
 
diff --git a/src/variable.c b/src/variable.c
index c36fea6e3..add1155c8 100644
--- a/src/variable.c
+++ b/src/variable.c
@@ -379,11 +379,11 @@ assign_class_name(mrb_state *mrb, struct RObject *obj, mrb_sym sym, mrb_value v)
   if (namespace_p(obj->tt) && namespace_p(mrb_type(v))) {
     struct RObject *c = mrb_obj_ptr(v);
     if (obj != c && ISUPPER(mrb_sym_name_len(mrb, sym, NULL)[0])) {
-      mrb_sym id_classname = mrb_intern_lit(mrb, "__classname__");
+      mrb_sym id_classname = MRB_SYM(__classname__);
       mrb_value o = mrb_obj_iv_get(mrb, c, id_classname);
 
       if (mrb_nil_p(o)) {
-        mrb_sym id_outer = mrb_intern_lit(mrb, "__outer__");
+        mrb_sym id_outer = MRB_SYM(__outer__);
         o = mrb_obj_iv_get(mrb, c, id_outer);
 
         if (mrb_nil_p(o)) {
@@ -643,8 +643,7 @@ mrb_mod_cv_get(mrb_state *mrb, struct RClass *c, mrb_sym sym)
   if (cls && cls->tt == MRB_TT_SCLASS) {
     mrb_value klass;
 
-    klass = mrb_obj_iv_get(mrb, (struct RObject *)cls,
-                           mrb_intern_lit(mrb, "__attached__"));
+    klass = mrb_obj_iv_get(mrb, (struct RObject *)cls, MRB_SYM(__attached__));
     c = mrb_class_ptr(klass);
     if (c->tt == MRB_TT_CLASS || c->tt == MRB_TT_MODULE) {
       given = FALSE;
@@ -688,8 +687,7 @@ mrb_mod_cv_set(mrb_state *mrb, struct RClass *c, mrb_sym sym, mrb_value v)
   if (cls && cls->tt == MRB_TT_SCLASS) {
     mrb_value klass;
 
-    klass = mrb_obj_iv_get(mrb, (struct RObject*)cls,
-                           mrb_intern_lit(mrb, "__attached__"));
+    klass = mrb_obj_iv_get(mrb, (struct RObject*)cls, MRB_SYM(__attached__));
     switch (mrb_type(klass)) {
     case MRB_TT_CLASS:
     case MRB_TT_MODULE:
@@ -803,7 +801,7 @@ L_RETRY:
     goto L_RETRY;
   }
   name = mrb_symbol_value(sym);
-  return mrb_funcall_argv(mrb, mrb_obj_value(base), mrb_intern_lit(mrb, "const_missing"), 1, &name);
+  return mrb_funcall_argv(mrb, mrb_obj_value(base), MRB_SYM(const_missing), 1, &name);
 }
 
 MRB_API mrb_value
@@ -829,7 +827,7 @@ mrb_vm_const_get(mrb_state *mrb, mrb_sym sym)
   while (c2 && c2->tt == MRB_TT_SCLASS) {
     mrb_value klass;
 
-    if (!iv_get(mrb, c2->iv, mrb_intern_lit(mrb, "__attached__"), &klass)) {
+    if (!iv_get(mrb, c2->iv, MRB_SYM(__attached__), &klass)) {
       c2 = NULL;
       break;
     }
@@ -1070,7 +1068,7 @@ outer_class(mrb_state *mrb, struct RClass *c)
 {
   mrb_value ov;
 
-  ov = mrb_obj_iv_get(mrb, (struct RObject*)c, mrb_intern_lit(mrb, "__outer__"));
+  ov = mrb_obj_iv_get(mrb, (struct RObject*)c, MRB_SYM(__outer__));
   if (mrb_nil_p(ov)) return NULL;
   switch (mrb_type(ov)) {
   case MRB_TT_CLASS:
@@ -1120,8 +1118,8 @@ mrb_class_find_path(mrb_state *mrb, struct RClass *c)
   str = mrb_sym_name_len(mrb, name, &len);
   mrb_str_cat(mrb, path, str, len);
   if (RSTRING_PTR(path)[0] != '#') {
-    iv_del(mrb, c->iv, mrb_intern_lit(mrb, "__outer__"), NULL);
-    iv_put(mrb, c->iv, mrb_intern_lit(mrb, "__classname__"), path);
+    iv_del(mrb, c->iv, MRB_SYM(__outer__), NULL);
+    iv_put(mrb, c->iv, MRB_SYM(__classname__), path);
     mrb_field_write_barrier_value(mrb, (struct RBasic*)c, path);
     path = mrb_str_dup(mrb, path);
   }
diff --git a/src/vm.c b/src/vm.c
index cc9a187b7..d032f2794 100644
--- a/src/vm.c
+++ b/src/vm.c
@@ -467,7 +467,7 @@ mrb_funcall_with_block(mrb_state *mrb, mrb_value self, mrb_sym mid, mrb_int argc
     c = mrb_class(mrb, self);
     m = mrb_method_search_vm(mrb, &c, mid);
     if (MRB_METHOD_UNDEF_P(m)) {
-      mrb_sym missing = mrb_intern_lit(mrb, "method_missing");
+      mrb_sym missing = MRB_SYM(method_missing);
       mrb_value args = mrb_ary_new_from_values(mrb, argc, argv);
       m = mrb_method_search_vm(mrb, &c, missing);
       if (MRB_METHOD_UNDEF_P(m)) {
@@ -1364,7 +1364,7 @@ RETRY_TRY_BLOCK:
       cls = mrb_class(mrb, recv);
       m = mrb_method_search_vm(mrb, &cls, mid);
       if (MRB_METHOD_UNDEF_P(m)) {
-        mrb_sym missing = mrb_intern_lit(mrb, "method_missing");
+        mrb_sym missing = MRB_SYM(method_missing);
         m = mrb_method_search_vm(mrb, &cls, missing);
         if (MRB_METHOD_UNDEF_P(m) || (missing == mrb->c->ci->mid && mrb_obj_eq(mrb, regs[0], recv))) {
           mrb_value args = (argc < 0) ? regs[a+1] : mrb_ary_new_from_values(mrb, c, regs+a+1);
@@ -1547,7 +1547,7 @@ RETRY_TRY_BLOCK:
       cls = target_class->super;
       m = mrb_method_search_vm(mrb, &cls, mid);
       if (MRB_METHOD_UNDEF_P(m)) {
-        mrb_sym missing = mrb_intern_lit(mrb, "method_missing");
+        mrb_sym missing = MRB_SYM(method_missing);
 
         if (mid != missing) {
           cls = mrb_class(mrb, recv);