diff --git a/mrblib/00class.rb b/mrblib/00class.rb
index c0cc97910..cb6d98738 100644
--- a/mrblib/00class.rb
+++ b/mrblib/00class.rb
@@ -7,8 +7,3 @@ class BasicObject
     end
   end
 end
-
-class Module
-  # 15.2.2.4.11
-  alias attr attr_reader
-end
diff --git a/src/class.c b/src/class.c
index b4caacb49..05a3c75ab 100644
--- a/src/class.c
+++ b/src/class.c
@@ -3228,6 +3228,7 @@ mrb_init_class(mrb_state *mrb)
   mrb_define_method_id(mrb, mod, MRB_SYM(attr_accessor),                   mrb_mod_attr_accessor,    MRB_ARGS_ANY());  /* 15.2.2.4.12 */
   mrb_define_method_id(mrb, mod, MRB_SYM(attr_reader),                     mrb_mod_attr_reader,      MRB_ARGS_ANY());  /* 15.2.2.4.13 */
   mrb_define_method_id(mrb, mod, MRB_SYM(attr_writer),                     mrb_mod_attr_writer,      MRB_ARGS_ANY());  /* 15.2.2.4.14 */
+  mrb_define_alias_id(mrb, mod, MRB_SYM(attr), MRB_SYM(attr_reader));                                                  /* 15.2.2.4.11 */
   mrb_define_method_id(mrb, mod, MRB_SYM(to_s),                            mrb_mod_to_s,             MRB_ARGS_NONE());
   mrb_define_method_id(mrb, mod, MRB_SYM(inspect),                         mrb_mod_to_s,             MRB_ARGS_NONE());
   mrb_define_method_id(mrb, mod, MRB_SYM(alias_method),                    mrb_mod_alias,            MRB_ARGS_ANY());  /* 15.2.2.4.8 */