diff --git a/mrbgems/mruby-bin-debugger/tools/mrdb/apiprint.c b/mrbgems/mruby-bin-debugger/tools/mrdb/apiprint.c
index 9093a4f0e..ffa28e02f 100644
--- a/mrbgems/mruby-bin-debugger/tools/mrdb/apiprint.c
+++ b/mrbgems/mruby-bin-debugger/tools/mrdb/apiprint.c
@@ -72,7 +72,7 @@ mrb_debug_eval(mrb_state *mrb, mrb_debug_context *dbg, const char *expr, size_t
   }
 
   if (exc) {
-    *exc = mrb_obj_is_kind_of(mrb, v, mrb->eException_class);
+    *exc = mrb_obj_is_kind_of(mrb, v, E_EXCEPTION);
   }
 
   s = mrb_inspect(mrb, v);
diff --git a/mrbgems/mruby-bin-debugger/tools/mrdb/cmdmisc.c b/mrbgems/mruby-bin-debugger/tools/mrdb/cmdmisc.c
index 0714f3f21..5739dedda 100644
--- a/mrbgems/mruby-bin-debugger/tools/mrdb/cmdmisc.c
+++ b/mrbgems/mruby-bin-debugger/tools/mrdb/cmdmisc.c
@@ -500,7 +500,7 @@ dbgcmd_quit(mrb_state *mrb, mrdb_state *mrdb)
 
   if (mrdb->dbg->xm == DBG_QUIT) {
     struct RClass *exc;
-    exc = mrb_define_class(mrb, "DebuggerExit", mrb->eException_class);
+    exc = mrb_define_class(mrb, "DebuggerExit", E_EXCEPTION);
     mrb_raise(mrb, exc, "Exit mrdb");
   }
   return DBGST_PROMPT;
diff --git a/mrbgems/mruby-bin-debugger/tools/mrdb/cmdrun.c b/mrbgems/mruby-bin-debugger/tools/mrdb/cmdrun.c
index fe8cf0aa7..1cd463eb0 100644
--- a/mrbgems/mruby-bin-debugger/tools/mrdb/cmdrun.c
+++ b/mrbgems/mruby-bin-debugger/tools/mrdb/cmdrun.c
@@ -19,7 +19,7 @@ dbgcmd_run(mrb_state *mrb, mrdb_state *mrdb)
     if (dbg->xphase == DBG_PHASE_RUNNING){
       struct RClass *exc;
       puts("Start it from the beginning");
-      exc = mrb_define_class(mrb, "DebuggerRestart", mrb->eException_class);
+      exc = mrb_define_class(mrb, "DebuggerRestart", E_EXCEPTION);
       mrb_raise(mrb, exc, "Restart mrdb");
     }
   }
diff --git a/mrbgems/mruby-dir/src/dir.c b/mrbgems/mruby-dir/src/dir.c
index 455c17bd3..d7d00436a 100644
--- a/mrbgems/mruby-dir/src/dir.c
+++ b/mrbgems/mruby-dir/src/dir.c
@@ -312,7 +312,7 @@ mrb_mruby_dir_gem_init(mrb_state *mrb)
   mrb_define_method(mrb, d, "seek",       mrb_dir_seek,   MRB_ARGS_REQ(1));
   mrb_define_method(mrb, d, "tell",       mrb_dir_tell,   MRB_ARGS_NONE());
 
-  mrb_define_class(mrb, "IOError", mrb->eStandardError_class);
+  mrb_define_class(mrb, "IOError", E_STANDARD_ERROR);
 }
 
 void
diff --git a/mrbgems/mruby-errno/src/errno.c b/mrbgems/mruby-errno/src/errno.c
index 97132b4b5..5e9950472 100644
--- a/mrbgems/mruby-errno/src/errno.c
+++ b/mrbgems/mruby-errno/src/errno.c
@@ -296,11 +296,9 @@ mrb_sce_sys_fail(mrb_state *mrb, mrb_value cls)
 void
 mrb_mruby_errno_gem_init(mrb_state *mrb)
 {
-  struct RClass *e, *eno, *sce, *ste;
+  struct RClass *e, *eno, *sce;
 
-  ste = mrb->eStandardError_class;
-
-  sce = mrb_define_class(mrb, "SystemCallError", ste);
+  sce = mrb_define_class(mrb, "SystemCallError", E_STANDARD_ERROR);
   mrb_define_class_method(mrb, sce, "_sys_fail", mrb_sce_sys_fail, MRB_ARGS_REQ(1));
   mrb_define_method(mrb, sce, "errno", mrb_sce_errno, MRB_ARGS_NONE());
   mrb_define_method(mrb, sce, "initialize", mrb_sce_init_m, MRB_ARGS_ARG(1, 1));
diff --git a/mrbgems/mruby-exit/src/mruby-exit.c b/mrbgems/mruby-exit/src/mruby-exit.c
index 658d188e6..24311f12f 100644
--- a/mrbgems/mruby-exit/src/mruby-exit.c
+++ b/mrbgems/mruby-exit/src/mruby-exit.c
@@ -72,7 +72,7 @@ f_exit_bang(mrb_state *mrb, mrb_value self)
 void
 mrb_mruby_exit_gem_init(mrb_state* mrb)
 {
-  mrb_define_class_id(mrb, MRB_SYM(SystemExit), mrb->eException_class);
+  mrb_define_class_id(mrb, MRB_SYM(SystemExit), E_EXCEPTION);
   mrb_define_method_id(mrb, mrb->kernel_module, MRB_SYM(exit), f_exit, MRB_ARGS_OPT(1));
   mrb_define_method_id(mrb, mrb->kernel_module, MRB_SYM_B(exit), f_exit_bang, MRB_ARGS_OPT(1));
 }
diff --git a/mrbgems/mruby-fiber/src/fiber.c b/mrbgems/mruby-fiber/src/fiber.c
index 33913c108..cf02f133b 100644
--- a/mrbgems/mruby-fiber/src/fiber.c
+++ b/mrbgems/mruby-fiber/src/fiber.c
@@ -471,7 +471,7 @@ mrb_mruby_fiber_gem_init(mrb_state* mrb)
   mrb_define_class_method(mrb, c, "yield", fiber_yield, MRB_ARGS_ANY());
   mrb_define_class_method(mrb, c, "current", fiber_current, MRB_ARGS_NONE());
 
-  mrb_define_class(mrb, "FiberError", mrb->eStandardError_class);
+  mrb_define_class(mrb, "FiberError", E_STANDARD_ERROR);
 }
 
 void
diff --git a/mrbgems/mruby-math/src/math.c b/mrbgems/mruby-math/src/math.c
index 1ae925c51..75f0a2202 100644
--- a/mrbgems/mruby-math/src/math.c
+++ b/mrbgems/mruby-math/src/math.c
@@ -670,7 +670,7 @@ mrb_mruby_math_gem_init(mrb_state* mrb)
   struct RClass *mrb_math;
   mrb_math = mrb_define_module(mrb, "Math");
 
-  mrb_define_class_under_id(mrb, mrb_math, MRB_SYM(DomainError), mrb->eStandardError_class);
+  mrb_define_class_under_id(mrb, mrb_math, MRB_SYM(DomainError), E_STANDARD_ERROR);
 
 #ifdef M_PI
   mrb_define_const_id(mrb, mrb_math, MRB_SYM(PI), mrb_float_value(mrb, M_PI));
diff --git a/src/class.c b/src/class.c
index 6cd40cfd3..9ac27a92d 100644
--- a/src/class.c
+++ b/src/class.c
@@ -678,16 +678,16 @@ mrb_exc_get_id(mrb_state *mrb, mrb_sym name)
   mrb_value c = mrb_const_get(mrb, mrb_obj_value(mrb->object_class), name);
 
   if (!mrb_class_p(c)) {
-    mrb_raise(mrb, mrb->eException_class, "exception corrupted");
+    mrb_raise(mrb, E_EXCEPTION, "exception corrupted");
   }
   exc = e = mrb_class_ptr(c);
 
   while (e) {
-    if (e == mrb->eException_class)
+    if (e == E_EXCEPTION)
       return exc;
     e = e->super;
   }
-  return mrb->eException_class;
+  return E_EXCEPTION;
 }
 
 MRB_API struct RClass*
diff --git a/src/error.c b/src/error.c
index 1e74f6c46..c40ea75c9 100644
--- a/src/error.c
+++ b/src/error.c
@@ -208,7 +208,7 @@ mrb_exc_raise(mrb_state *mrb, mrb_value exc)
     mrb->exc = mrb_obj_ptr(exc);
   }
   else {
-    if (!mrb_obj_is_kind_of(mrb, exc, mrb->eException_class)) {
+    if (!mrb_obj_is_kind_of(mrb, exc, E_EXCEPTION)) {
       mrb_raise(mrb, E_TYPE_ERROR, "exception object expected");
     }
     mrb_exc_set(mrb, exc);
@@ -499,8 +499,8 @@ exception_call:
       break;
   }
   if (argc > 0) {
-    if (!mrb_obj_is_kind_of(mrb, mesg, mrb->eException_class))
-      mrb_raise(mrb, mrb->eException_class, "exception object expected");
+    if (!mrb_obj_is_kind_of(mrb, mesg, E_EXCEPTION))
+      mrb_raise(mrb, E_EXCEPTION, "exception object expected");
     if (argc > 2)
       set_backtrace(mrb, mesg, argv[2]);
   }
@@ -683,8 +683,8 @@ mrb_init_exception(mrb_state *mrb)
   mrb_define_method(mrb, exception, "set_backtrace",   exc_set_backtrace, MRB_ARGS_REQ(1));
 
   mrb->eStandardError_class = mrb_define_class(mrb, "StandardError", mrb->eException_class); /* 15.2.23 */
-  mrb_define_class(mrb, "RuntimeError", mrb->eStandardError_class);          /* 15.2.28 */
-  script_error = mrb_define_class(mrb, "ScriptError", mrb->eException_class);                /* 15.2.37 */
+  mrb_define_class(mrb, "RuntimeError", E_STANDARD_ERROR);          /* 15.2.28 */
+  script_error = mrb_define_class(mrb, "ScriptError", exception);                /* 15.2.37 */
   mrb_define_class(mrb, "SyntaxError", script_error);                                        /* 15.2.38 */
   stack_error = mrb_define_class(mrb, "SystemStackError", exception);
   mrb->stack_err = mrb_obj_ptr(mrb_exc_new_lit(mrb, stack_error, "stack level too deep"));