diff --git a/array.c b/array.c
index 28fd109285..dc1dad6d16 100644
--- a/array.c
+++ b/array.c
@@ -873,7 +873,7 @@ enum ary_take_pos_flags
 };
 
 static VALUE
-ary_take_first_or_last(int argc, VALUE *argv, VALUE ary, enum ary_take_pos_flags last)
+ary_take_first_or_last(int argc, const VALUE *argv, VALUE ary, enum ary_take_pos_flags last)
 {
     VALUE nv;
     long n;
@@ -1252,7 +1252,7 @@ rb_ary_subseq(VALUE ary, long beg, long len)
  */
 
 VALUE
-rb_ary_aref(int argc, VALUE *argv, VALUE ary)
+rb_ary_aref(int argc, const VALUE *argv, VALUE ary)
 {
     VALUE arg;
     long beg, len;
@@ -1347,7 +1347,7 @@ rb_ary_first(int argc, VALUE *argv, VALUE ary)
  */
 
 VALUE
-rb_ary_last(int argc, VALUE *argv, VALUE ary)
+rb_ary_last(int argc, const VALUE *argv, VALUE ary)
 {
     if (argc == 0) {
 	long len = RARRAY_LEN(ary);
@@ -2736,7 +2736,7 @@ rb_ary_collect_bang(VALUE ary)
 }
 
 VALUE
-rb_get_values_at(VALUE obj, long olen, int argc, VALUE *argv, VALUE (*func) (VALUE, long))
+rb_get_values_at(VALUE obj, long olen, int argc, const VALUE *argv, VALUE (*func) (VALUE, long))
 {
     VALUE result = rb_ary_new2(argc);
     long beg, len, i, j;
diff --git a/class.c b/class.c
index be59e68829..feeed889dd 100644
--- a/class.c
+++ b/class.c
@@ -1141,7 +1141,7 @@ method_entry_i(st_data_t key, st_data_t value, st_data_t data)
 }
 
 static VALUE
-class_instance_method_list(int argc, VALUE *argv, VALUE mod, int obj, int (*func) (st_data_t, st_data_t, st_data_t))
+class_instance_method_list(int argc, const VALUE *argv, VALUE mod, int obj, int (*func) (st_data_t, st_data_t, st_data_t))
 {
     VALUE ary;
     int recur, prepended = 0;
@@ -1203,7 +1203,7 @@ class_instance_method_list(int argc, VALUE *argv, VALUE mod, int obj, int (*func
  */
 
 VALUE
-rb_class_instance_methods(int argc, VALUE *argv, VALUE mod)
+rb_class_instance_methods(int argc, const VALUE *argv, VALUE mod)
 {
     return class_instance_method_list(argc, argv, mod, 0, ins_methods_i);
 }
@@ -1218,7 +1218,7 @@ rb_class_instance_methods(int argc, VALUE *argv, VALUE mod)
  */
 
 VALUE
-rb_class_protected_instance_methods(int argc, VALUE *argv, VALUE mod)
+rb_class_protected_instance_methods(int argc, const VALUE *argv, VALUE mod)
 {
     return class_instance_method_list(argc, argv, mod, 0, ins_methods_prot_i);
 }
@@ -1241,7 +1241,7 @@ rb_class_protected_instance_methods(int argc, VALUE *argv, VALUE mod)
  */
 
 VALUE
-rb_class_private_instance_methods(int argc, VALUE *argv, VALUE mod)
+rb_class_private_instance_methods(int argc, const VALUE *argv, VALUE mod)
 {
     return class_instance_method_list(argc, argv, mod, 0, ins_methods_priv_i);
 }
@@ -1256,7 +1256,7 @@ rb_class_private_instance_methods(int argc, VALUE *argv, VALUE mod)
  */
 
 VALUE
-rb_class_public_instance_methods(int argc, VALUE *argv, VALUE mod)
+rb_class_public_instance_methods(int argc, const VALUE *argv, VALUE mod)
 {
     return class_instance_method_list(argc, argv, mod, 0, ins_methods_pub_i);
 }
@@ -1292,7 +1292,7 @@ rb_class_public_instance_methods(int argc, VALUE *argv, VALUE mod)
  */
 
 VALUE
-rb_obj_methods(int argc, VALUE *argv, VALUE obj)
+rb_obj_methods(int argc, const VALUE *argv, VALUE obj)
 {
     rb_check_arity(argc, 0, 1);
     if (argc > 0 && !RTEST(argv[0])) {
@@ -1311,7 +1311,7 @@ rb_obj_methods(int argc, VALUE *argv, VALUE obj)
  */
 
 VALUE
-rb_obj_protected_methods(int argc, VALUE *argv, VALUE obj)
+rb_obj_protected_methods(int argc, const VALUE *argv, VALUE obj)
 {
     return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_prot_i);
 }
@@ -1326,7 +1326,7 @@ rb_obj_protected_methods(int argc, VALUE *argv, VALUE obj)
  */
 
 VALUE
-rb_obj_private_methods(int argc, VALUE *argv, VALUE obj)
+rb_obj_private_methods(int argc, const VALUE *argv, VALUE obj)
 {
     return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_priv_i);
 }
@@ -1341,7 +1341,7 @@ rb_obj_private_methods(int argc, VALUE *argv, VALUE obj)
  */
 
 VALUE
-rb_obj_public_methods(int argc, VALUE *argv, VALUE obj)
+rb_obj_public_methods(int argc, const VALUE *argv, VALUE obj)
 {
     return class_instance_method_list(argc, argv, CLASS_OF(obj), 1, ins_methods_pub_i);
 }
@@ -1380,7 +1380,7 @@ rb_obj_public_methods(int argc, VALUE *argv, VALUE obj)
  */
 
 VALUE
-rb_obj_singleton_methods(int argc, VALUE *argv, VALUE obj)
+rb_obj_singleton_methods(int argc, const VALUE *argv, VALUE obj)
 {
     VALUE recur, ary, klass, origin;
     st_table *list, *mtbl;
diff --git a/constant.h b/constant.h
index 153654604b..77dd696b7e 100644
--- a/constant.h
+++ b/constant.h
@@ -23,8 +23,8 @@ typedef struct rb_const_entry_struct {
     const VALUE file;             /* should be mark */
 } rb_const_entry_t;
 
-VALUE rb_mod_private_constant(int argc, VALUE *argv, VALUE obj);
-VALUE rb_mod_public_constant(int argc, VALUE *argv, VALUE obj);
+VALUE rb_mod_private_constant(int argc, const VALUE *argv, VALUE obj);
+VALUE rb_mod_public_constant(int argc, const VALUE *argv, VALUE obj);
 void rb_free_const_table(st_table *tbl);
 VALUE rb_public_const_get(VALUE klass, ID id);
 VALUE rb_public_const_get_at(VALUE klass, ID id);
diff --git a/cont.c b/cont.c
index 4cb22b33e4..3df3aea22c 100644
--- a/cont.c
+++ b/cont.c
@@ -938,7 +938,7 @@ rb_callcc(VALUE self)
 }
 
 static VALUE
-make_passing_arg(int argc, VALUE *argv)
+make_passing_arg(int argc, const VALUE *argv)
 {
     switch (argc) {
       case 0:
@@ -1257,7 +1257,7 @@ return_fiber(void)
     }
 }
 
-VALUE rb_fiber_transfer(VALUE fib, int argc, VALUE *argv);
+VALUE rb_fiber_transfer(VALUE fib, int argc, const VALUE *argv);
 
 static void
 rb_fiber_terminate(rb_fiber_t *fib)
@@ -1405,7 +1405,7 @@ fiber_store(rb_fiber_t *next_fib)
 }
 
 static inline VALUE
-fiber_switch(VALUE fibval, int argc, VALUE *argv, int is_resume)
+fiber_switch(VALUE fibval, int argc, const VALUE *argv, int is_resume)
 {
     VALUE value;
     rb_fiber_t *fib;
@@ -1480,13 +1480,13 @@ fiber_switch(VALUE fibval, int argc, VALUE *argv, int is_resume)
 }
 
 VALUE
-rb_fiber_transfer(VALUE fib, int argc, VALUE *argv)
+rb_fiber_transfer(VALUE fib, int argc, const VALUE *argv)
 {
     return fiber_switch(fib, argc, argv, 0);
 }
 
 VALUE
-rb_fiber_resume(VALUE fibval, int argc, VALUE *argv)
+rb_fiber_resume(VALUE fibval, int argc, const VALUE *argv)
 {
     rb_fiber_t *fib;
     GetFiberPtr(fibval, fib);
@@ -1502,7 +1502,7 @@ rb_fiber_resume(VALUE fibval, int argc, VALUE *argv)
 }
 
 VALUE
-rb_fiber_yield(int argc, VALUE *argv)
+rb_fiber_yield(int argc, const VALUE *argv)
 {
     return rb_fiber_transfer(return_fiber(), argc, argv);
 }
diff --git a/enumerator.c b/enumerator.c
index d66233f376..d405c2a1eb 100644
--- a/enumerator.c
+++ b/enumerator.c
@@ -267,7 +267,7 @@ enumerator_allocate(VALUE klass)
 }
 
 static VALUE
-enumerator_init(VALUE enum_obj, VALUE obj, VALUE meth, int argc, VALUE *argv, rb_enumerator_size_func *size_fn, VALUE size)
+enumerator_init(VALUE enum_obj, VALUE obj, VALUE meth, int argc, const VALUE *argv, rb_enumerator_size_func *size_fn, VALUE size)
 {
     struct enumerator *ptr;
 
@@ -398,16 +398,16 @@ enumerator_init_copy(VALUE obj, VALUE orig)
  * For backwards compatibility; use rb_enumeratorize_with_size
  */
 VALUE
-rb_enumeratorize(VALUE obj, VALUE meth, int argc, VALUE *argv)
+rb_enumeratorize(VALUE obj, VALUE meth, int argc, const VALUE *argv)
 {
     return rb_enumeratorize_with_size(obj, meth, argc, argv, 0);
 }
 
 static VALUE
-lazy_to_enum_i(VALUE self, VALUE meth, int argc, VALUE *argv, rb_enumerator_size_func *size_fn);
+lazy_to_enum_i(VALUE self, VALUE meth, int argc, const VALUE *argv, rb_enumerator_size_func *size_fn);
 
 VALUE
-rb_enumeratorize_with_size(VALUE obj, VALUE meth, int argc, VALUE *argv, rb_enumerator_size_func *size_fn)
+rb_enumeratorize_with_size(VALUE obj, VALUE meth, int argc, const VALUE *argv, rb_enumerator_size_func *size_fn)
 {
     /* Similar effect as calling obj.to_enum, i.e. dispatching to either
        Kernel#to_enum vs Lazy#to_enum */
@@ -1459,7 +1459,7 @@ enumerable_lazy(VALUE obj)
 }
 
 static VALUE
-lazy_to_enum_i(VALUE obj, VALUE meth, int argc, VALUE *argv, rb_enumerator_size_func *size_fn)
+lazy_to_enum_i(VALUE obj, VALUE meth, int argc, const VALUE *argv, rb_enumerator_size_func *size_fn)
 {
     return enumerator_init(enumerator_allocate(rb_cLazy),
 			   obj, meth, argc, argv, size_fn, Qnil);
diff --git a/eval.c b/eval.c
index ba15de546f..7a8dce3d71 100644
--- a/eval.c
+++ b/eval.c
@@ -571,7 +571,7 @@ rb_longjmp(int tag, volatile VALUE mesg, VALUE cause)
     JUMP_TAG(tag);
 }
 
-static VALUE make_exception(int argc, VALUE *argv, int isstr);
+static VALUE make_exception(int argc, const VALUE *argv, int isstr);
 
 void
 rb_exc_raise(VALUE mesg)
@@ -668,7 +668,7 @@ rb_f_raise(int argc, VALUE *argv)
 }
 
 static VALUE
-make_exception(int argc, VALUE *argv, int isstr)
+make_exception(int argc, const VALUE *argv, int isstr)
 {
     VALUE mesg, exc;
     ID exception;
@@ -719,7 +719,7 @@ make_exception(int argc, VALUE *argv, int isstr)
 }
 
 VALUE
-rb_make_exception(int argc, VALUE *argv)
+rb_make_exception(int argc, const VALUE *argv)
 {
     return make_exception(argc, argv, TRUE);
 }
diff --git a/eval_intern.h b/eval_intern.h
index 508379e54d..163c87c881 100644
--- a/eval_intern.h
+++ b/eval_intern.h
@@ -229,8 +229,8 @@ int rb_threadptr_reset_raised(rb_thread_t *th);
 #define rb_thread_raised_p(th, f)     (((th)->raised_flag & (f)) != 0)
 #define rb_thread_raised_clear(th)    ((th)->raised_flag = 0)
 
-VALUE rb_f_eval(int argc, VALUE *argv, VALUE self);
-VALUE rb_make_exception(int argc, VALUE *argv);
+VALUE rb_f_eval(int argc, const VALUE *argv, VALUE self);
+VALUE rb_make_exception(int argc, const VALUE *argv);
 
 NORETURN(void rb_method_name_error(VALUE, VALUE));
 
@@ -240,7 +240,7 @@ NORETURN(void rb_print_undef(VALUE, ID, int));
 NORETURN(void rb_print_undef_str(VALUE, VALUE));
 NORETURN(void rb_vm_localjump_error(const char *,VALUE, int));
 NORETURN(void rb_vm_jump_tag_but_local_jump(int));
-NORETURN(void rb_raise_method_missing(rb_thread_t *th, int argc, VALUE *argv,
+NORETURN(void rb_raise_method_missing(rb_thread_t *th, int argc, const VALUE *argv,
 				      VALUE obj, int call_status));
 
 VALUE rb_vm_make_jump_tag_but_local_jump(int state, VALUE val);
diff --git a/file.c b/file.c
index 1573a53aa9..a2d6681700 100644
--- a/file.c
+++ b/file.c
@@ -3569,7 +3569,7 @@ rb_file_expand_path_fast(VALUE fname, VALUE dname)
  */
 
 VALUE
-rb_file_s_expand_path(int argc, VALUE *argv)
+rb_file_s_expand_path(int argc, const VALUE *argv)
 {
     VALUE fname, dname;
 
@@ -3602,7 +3602,7 @@ rb_file_absolute_path(VALUE fname, VALUE dname)
  */
 
 VALUE
-rb_file_s_absolute_path(int argc, VALUE *argv)
+rb_file_s_absolute_path(int argc, const VALUE *argv)
 {
     VALUE fname, dname;
 
diff --git a/gc.c b/gc.c
index 8ab7fbfa20..c61d51765b 100644
--- a/gc.c
+++ b/gc.c
@@ -3365,7 +3365,7 @@ ruby_stack_check(void)
 
 ATTRIBUTE_NO_ADDRESS_SAFETY_ANALYSIS
 static void
-mark_locations_array(rb_objspace_t *objspace, register VALUE *x, register long n)
+mark_locations_array(rb_objspace_t *objspace, register const VALUE *x, register long n)
 {
     VALUE v;
     while (n--) {
@@ -3376,7 +3376,7 @@ mark_locations_array(rb_objspace_t *objspace, register VALUE *x, register long n
 }
 
 static void
-gc_mark_locations(rb_objspace_t *objspace, VALUE *start, VALUE *end)
+gc_mark_locations(rb_objspace_t *objspace, const VALUE *start, const VALUE *end)
 {
     long n;
 
@@ -3386,7 +3386,7 @@ gc_mark_locations(rb_objspace_t *objspace, VALUE *start, VALUE *end)
 }
 
 void
-rb_gc_mark_locations(VALUE *start, VALUE *end)
+rb_gc_mark_locations(const VALUE *start, const VALUE *end)
 {
     gc_mark_locations(&rb_objspace, start, end);
 }
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index 387f000c66..d3f2bdb6d7 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -56,7 +56,7 @@ void rb_ary_free(VALUE);
 void rb_ary_modify(VALUE);
 VALUE rb_ary_freeze(VALUE);
 VALUE rb_ary_shared_with_p(VALUE, VALUE);
-VALUE rb_ary_aref(int, VALUE*, VALUE);
+VALUE rb_ary_aref(int, const VALUE*, VALUE);
 VALUE rb_ary_subseq(VALUE, long, long);
 void rb_ary_store(VALUE, long, VALUE);
 VALUE rb_ary_dup(VALUE);
@@ -85,7 +85,7 @@ VALUE rb_ary_rassoc(VALUE, VALUE);
 VALUE rb_ary_includes(VALUE, VALUE);
 VALUE rb_ary_cmp(VALUE, VALUE);
 VALUE rb_ary_replace(VALUE copy, VALUE orig);
-VALUE rb_get_values_at(VALUE, long, int, VALUE*, VALUE(*)(VALUE,long));
+VALUE rb_get_values_at(VALUE, long, int, const VALUE*, VALUE(*)(VALUE,long));
 VALUE rb_ary_resize(VALUE ary, long len);
 #define rb_ary_new2 rb_ary_new_capa
 #define rb_ary_new3 rb_ary_new_from_args
@@ -201,11 +201,11 @@ VALUE rb_include_class_new(VALUE, VALUE);
 VALUE rb_mod_included_modules(VALUE);
 VALUE rb_mod_include_p(VALUE, VALUE);
 VALUE rb_mod_ancestors(VALUE);
-VALUE rb_class_instance_methods(int, VALUE*, VALUE);
-VALUE rb_class_public_instance_methods(int, VALUE*, VALUE);
-VALUE rb_class_protected_instance_methods(int, VALUE*, VALUE);
-VALUE rb_class_private_instance_methods(int, VALUE*, VALUE);
-VALUE rb_obj_singleton_methods(int, VALUE*, VALUE);
+VALUE rb_class_instance_methods(int, const VALUE*, VALUE);
+VALUE rb_class_public_instance_methods(int, const VALUE*, VALUE);
+VALUE rb_class_protected_instance_methods(int, const VALUE*, VALUE);
+VALUE rb_class_private_instance_methods(int, const VALUE*, VALUE);
+VALUE rb_obj_singleton_methods(int, const VALUE*, VALUE);
 void rb_define_method_id(VALUE, ID, VALUE (*)(ANYARGS), int);
 void rb_frozen_class_p(VALUE);
 void rb_undef(VALUE, ID);
@@ -218,16 +218,16 @@ int rb_cmpint(VALUE, VALUE, VALUE);
 NORETURN(void rb_cmperr(VALUE, VALUE));
 /* cont.c */
 VALUE rb_fiber_new(VALUE (*)(ANYARGS), VALUE);
-VALUE rb_fiber_resume(VALUE fib, int argc, VALUE *args);
-VALUE rb_fiber_yield(int argc, VALUE *args);
+VALUE rb_fiber_resume(VALUE fib, int argc, const VALUE *argv);
+VALUE rb_fiber_yield(int argc, const VALUE *argv);
 VALUE rb_fiber_current(void);
 VALUE rb_fiber_alive_p(VALUE);
 /* enum.c */
 VALUE rb_enum_values_pack(int, const VALUE*);
 /* enumerator.c */
-VALUE rb_enumeratorize(VALUE, VALUE, int, VALUE *);
+VALUE rb_enumeratorize(VALUE, VALUE, int, const VALUE *);
 typedef VALUE rb_enumerator_size_func(VALUE, VALUE, VALUE);
-VALUE rb_enumeratorize_with_size(VALUE, VALUE, int, VALUE *, rb_enumerator_size_func *);
+VALUE rb_enumeratorize_with_size(VALUE, VALUE, int, const VALUE *, rb_enumerator_size_func *);
 #ifndef RUBY_EXPORT
 #define rb_enumeratorize_with_size(obj, id, argc, argv, size_fn) \
     rb_enumeratorize_with_size(obj, id, argc, argv, (rb_enumerator_size_func *)(size_fn))
@@ -362,8 +362,8 @@ typedef fd_set rb_fdset_t;
 
 NORETURN(void rb_exc_raise(VALUE));
 NORETURN(void rb_exc_fatal(VALUE));
-VALUE rb_f_exit(int,VALUE*);
-VALUE rb_f_abort(int,VALUE*);
+VALUE rb_f_exit(int, const VALUE*);
+VALUE rb_f_abort(int, const VALUE*);
 void rb_remove_method(VALUE, const char*);
 void rb_remove_method_id(VALUE, ID);
 #define rb_disable_super(klass, name) ((void)0)
@@ -383,15 +383,15 @@ int rb_method_basic_definition_p(VALUE, ID);
 VALUE rb_eval_cmd(VALUE, VALUE, int);
 int rb_obj_respond_to(VALUE, ID, int);
 int rb_respond_to(VALUE, ID);
-VALUE rb_f_notimplement(int argc, VALUE *argv, VALUE obj);
+VALUE rb_f_notimplement(int argc, const VALUE *argv, VALUE obj);
 void rb_interrupt(void);
 VALUE rb_apply(VALUE, ID, VALUE);
 void rb_backtrace(void);
 ID rb_frame_this_func(void);
-VALUE rb_obj_instance_eval(int, VALUE*, VALUE);
-VALUE rb_obj_instance_exec(int, VALUE*, VALUE);
-VALUE rb_mod_module_eval(int, VALUE*, VALUE);
-VALUE rb_mod_module_exec(int, VALUE*, VALUE);
+VALUE rb_obj_instance_eval(int, const VALUE*, VALUE);
+VALUE rb_obj_instance_exec(int, const VALUE*, VALUE);
+VALUE rb_mod_module_eval(int, const VALUE*, VALUE);
+VALUE rb_mod_module_exec(int, const VALUE*, VALUE);
 void rb_load(VALUE, int);
 void rb_load_protect(VALUE, int, int*);
 NORETURN(void rb_jump_tag(int));
@@ -413,8 +413,8 @@ VALUE rb_proc_lambda_p(VALUE);
 VALUE rb_binding_new(void);
 VALUE rb_obj_method(VALUE, VALUE);
 VALUE rb_obj_is_method(VALUE);
-VALUE rb_method_call(int, VALUE*, VALUE);
-VALUE rb_method_call_with_block(int, VALUE *, VALUE, VALUE);
+VALUE rb_method_call(int, const VALUE*, VALUE);
+VALUE rb_method_call_with_block(int, const VALUE *, VALUE, VALUE);
 int rb_mod_method_arity(VALUE, ID);
 int rb_obj_method_arity(VALUE, ID);
 VALUE rb_protect(VALUE (*)(VALUE), VALUE, int*);
@@ -449,9 +449,9 @@ VALUE rb_exec_recursive_paired_outer(VALUE(*)(VALUE, VALUE, int),VALUE,VALUE,VAL
 /* dir.c */
 VALUE rb_dir_getwd(void);
 /* file.c */
-VALUE rb_file_s_expand_path(int, VALUE *);
+VALUE rb_file_s_expand_path(int, const VALUE *);
 VALUE rb_file_expand_path(VALUE, VALUE);
-VALUE rb_file_s_absolute_path(int, VALUE *);
+VALUE rb_file_s_absolute_path(int, const VALUE *);
 VALUE rb_file_absolute_path(VALUE, VALUE);
 VALUE rb_file_dirname(VALUE fname);
 int rb_find_file_ext_safe(VALUE*, const char* const*, int);
@@ -464,7 +464,7 @@ int rb_is_absolute_path(const char *);
 /* gc.c */
 NORETURN(void rb_memerror(void));
 int rb_during_gc(void);
-void rb_gc_mark_locations(VALUE*, VALUE*);
+void rb_gc_mark_locations(const VALUE*, const VALUE*);
 void rb_mark_tbl(struct st_table*);
 void rb_mark_set(struct st_table*);
 void rb_mark_hash(struct st_table*);
@@ -524,9 +524,9 @@ VALUE rb_io_eof(VALUE);
 VALUE rb_io_binmode(VALUE);
 VALUE rb_io_ascii8bit_binmode(VALUE);
 VALUE rb_io_addstr(VALUE, VALUE);
-VALUE rb_io_printf(int, VALUE*, VALUE);
-VALUE rb_io_print(int, VALUE*, VALUE);
-VALUE rb_io_puts(int, VALUE*, VALUE);
+VALUE rb_io_printf(int, const VALUE*, VALUE);
+VALUE rb_io_print(int, const VALUE*, VALUE);
+VALUE rb_io_puts(int, const VALUE*, VALUE);
 VALUE rb_io_fdopen(int, int, const char*);
 VALUE rb_io_get_io(VALUE);
 VALUE rb_file_open(const char*, const char*);
@@ -619,11 +619,11 @@ VALUE rb_sym_all_symbols(void);
 void rb_last_status_set(int status, rb_pid_t pid);
 VALUE rb_last_status_get(void);
 int rb_proc_exec(const char*);
-VALUE rb_f_exec(int,VALUE*);
+VALUE rb_f_exec(int, const VALUE*);
 rb_pid_t rb_waitpid(rb_pid_t pid, int *status, int flags);
 void rb_syswait(rb_pid_t pid);
-rb_pid_t rb_spawn(int, VALUE*);
-rb_pid_t rb_spawn_err(int, VALUE*, char*, size_t);
+rb_pid_t rb_spawn(int, const VALUE*);
+rb_pid_t rb_spawn_err(int, const VALUE*, char*, size_t);
 VALUE rb_proc_times(VALUE);
 VALUE rb_detach_process(rb_pid_t pid);
 /* range.c */
@@ -666,7 +666,7 @@ VALUE rb_get_argv(void);
 void *rb_load_file(const char*);
 void *rb_load_file_str(VALUE);
 /* signal.c */
-VALUE rb_f_kill(int, VALUE*);
+VALUE rb_f_kill(int, const VALUE*);
 #ifdef POSIX_SIGNAL
 #define posix_signal ruby_posix_signal
 RETSIGTYPE (*posix_signal(int, RETSIGTYPE (*)(int)))(int);
@@ -874,8 +874,8 @@ VALUE rb_class_name(VALUE);
 void rb_autoload(VALUE, ID, const char*);
 VALUE rb_autoload_load(VALUE, ID);
 VALUE rb_autoload_p(VALUE, ID);
-VALUE rb_f_trace_var(int, VALUE*);
-VALUE rb_f_untrace_var(int, VALUE*);
+VALUE rb_f_trace_var(int, const VALUE*);
+VALUE rb_f_untrace_var(int, const VALUE*);
 VALUE rb_f_global_variables(void);
 void rb_alias_variable(ID, ID);
 struct st_table* rb_generic_ivar_table(VALUE);
@@ -892,7 +892,7 @@ VALUE rb_obj_remove_instance_variable(VALUE, VALUE);
 void *rb_mod_const_at(VALUE, void*);
 void *rb_mod_const_of(VALUE, void*);
 VALUE rb_const_list(void*);
-VALUE rb_mod_constants(int, VALUE *, VALUE);
+VALUE rb_mod_constants(int, const VALUE *, VALUE);
 VALUE rb_mod_remove_const(VALUE, VALUE);
 int rb_const_defined(VALUE, ID);
 int rb_const_defined_at(VALUE, ID);
@@ -909,7 +909,7 @@ VALUE rb_cvar_get(VALUE, ID);
 void rb_cv_set(VALUE, const char*, VALUE);
 VALUE rb_cv_get(VALUE, const char*);
 void rb_define_class_variable(VALUE, const char*, VALUE);
-VALUE rb_mod_class_variables(int, VALUE*, VALUE);
+VALUE rb_mod_class_variables(int, const VALUE*, VALUE);
 VALUE rb_mod_remove_cvar(VALUE, VALUE);
 
 ID rb_frame_callee(void);
@@ -917,7 +917,7 @@ VALUE rb_str_succ(VALUE);
 VALUE rb_time_succ(VALUE);
 int rb_frame_method_id_and_class(ID *idp, VALUE *klassp);
 VALUE rb_make_backtrace(void);
-VALUE rb_make_exception(int, VALUE*);
+VALUE rb_make_exception(int, const VALUE*);
 
 /* deprecated */
 DEPRECATED(void rb_frame_pop(void));
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 7c7cb67d99..ff97d36b3d 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -1350,7 +1350,7 @@ void  rb_gvar_readonly_setter(VALUE val, ID id, void *data, struct rb_global_var
 void rb_define_variable(const char*,VALUE*);
 void rb_define_virtual_variable(const char*,VALUE(*)(ANYARGS),void(*)(ANYARGS));
 void rb_define_hooked_variable(const char*,VALUE*,VALUE(*)(ANYARGS),void(*)(ANYARGS));
-void rb_define_readonly_variable(const char*,VALUE*);
+void rb_define_readonly_variable(const char*,const VALUE*);
 void rb_define_const(VALUE,const char*,VALUE);
 void rb_define_global_const(const char*,VALUE);
 
diff --git a/internal.h b/internal.h
index 2c1c6a3dfc..fc0f0d573e 100644
--- a/internal.h
+++ b/internal.h
@@ -465,7 +465,7 @@ RCLASS_SET_SUPER(VALUE klass, VALUE super)
 struct vtm; /* defined by timev.h */
 
 /* array.c */
-VALUE rb_ary_last(int, VALUE *, VALUE);
+VALUE rb_ary_last(int, const VALUE *, VALUE);
 void rb_ary_set_len(VALUE, long);
 void rb_ary_delete_same(VALUE, VALUE);
 
@@ -480,10 +480,10 @@ void rb_class_foreach_subclass(VALUE klass, void(*f)(VALUE));
 void rb_class_detach_subclasses(VALUE);
 void rb_class_detach_module_subclasses(VALUE);
 void rb_class_remove_from_module_subclasses(VALUE);
-VALUE rb_obj_methods(int argc, VALUE *argv, VALUE obj);
-VALUE rb_obj_protected_methods(int argc, VALUE *argv, VALUE obj);
-VALUE rb_obj_private_methods(int argc, VALUE *argv, VALUE obj);
-VALUE rb_obj_public_methods(int argc, VALUE *argv, VALUE obj);
+VALUE rb_obj_methods(int argc, const VALUE *argv, VALUE obj);
+VALUE rb_obj_protected_methods(int argc, const VALUE *argv, VALUE obj);
+VALUE rb_obj_private_methods(int argc, const VALUE *argv, VALUE obj);
+VALUE rb_obj_public_methods(int argc, const VALUE *argv, VALUE obj);
 int rb_obj_basic_to_s_p(VALUE);
 VALUE rb_special_singleton_class(VALUE);
 VALUE rb_singleton_class_clone_and_attach(VALUE obj, VALUE attach);
@@ -649,7 +649,7 @@ VALUE rb_math_cos(VALUE);
 VALUE rb_math_cosh(VALUE);
 VALUE rb_math_exp(VALUE);
 VALUE rb_math_hypot(VALUE, VALUE);
-VALUE rb_math_log(int argc, VALUE *argv);
+VALUE rb_math_log(int argc, const VALUE *argv);
 VALUE rb_math_sin(VALUE);
 VALUE rb_math_sinh(VALUE);
 #if 0
@@ -943,8 +943,8 @@ void Init_prelude(void);
 
 /* vm_backtrace.c */
 void Init_vm_backtrace(void);
-VALUE rb_vm_thread_backtrace(int argc, VALUE *argv, VALUE thval);
-VALUE rb_vm_thread_backtrace_locations(int argc, VALUE *argv, VALUE thval);
+VALUE rb_vm_thread_backtrace(int argc, const VALUE *argv, VALUE thval);
+VALUE rb_vm_thread_backtrace_locations(int argc, const VALUE *argv, VALUE thval);
 
 VALUE rb_make_backtrace(void);
 void rb_backtrace_print_as_bugreport(void);
diff --git a/io.c b/io.c
index 9900118818..77460c9a59 100644
--- a/io.c
+++ b/io.c
@@ -6845,7 +6845,7 @@ rb_io_init_copy(VALUE dest, VALUE io)
  */
 
 VALUE
-rb_io_printf(int argc, VALUE *argv, VALUE out)
+rb_io_printf(int argc, const VALUE *argv, VALUE out)
 {
     rb_io_write(out, rb_f_sprintf(argc, argv));
     return Qnil;
@@ -6904,7 +6904,7 @@ rb_f_printf(int argc, VALUE *argv)
  */
 
 VALUE
-rb_io_print(int argc, VALUE *argv, VALUE out)
+rb_io_print(int argc, const VALUE *argv, VALUE out)
 {
     int i;
     VALUE line;
@@ -6952,7 +6952,7 @@ rb_io_print(int argc, VALUE *argv, VALUE out)
  */
 
 static VALUE
-rb_f_print(int argc, VALUE *argv)
+rb_f_print(int argc, const VALUE *argv)
 {
     rb_io_print(argc, argv, rb_stdout);
     return Qnil;
@@ -7069,7 +7069,7 @@ io_puts_ary(VALUE ary, VALUE out, int recur)
  */
 
 VALUE
-rb_io_puts(int argc, VALUE *argv, VALUE out)
+rb_io_puts(int argc, const VALUE *argv, VALUE out)
 {
     int i;
     VALUE line;
diff --git a/iseq.c b/iseq.c
index 3b0c10b5c3..77507d83cf 100644
--- a/iseq.c
+++ b/iseq.c
@@ -1152,9 +1152,9 @@ id_to_name(ID id, VALUE default_value)
 }
 
 VALUE
-rb_insn_operand_intern(rb_iseq_t *iseq,
+rb_insn_operand_intern(const rb_iseq_t *iseq,
 		       VALUE insn, int op_no, VALUE op,
-		       int len, size_t pos, VALUE *pnop, VALUE child)
+		       int len, size_t pos, const VALUE *pnop, VALUE child)
 {
     const char *types = insn_op_types(insn);
     char type = types[op_no];
@@ -1172,7 +1172,7 @@ rb_insn_operand_intern(rb_iseq_t *iseq,
       case TS_LINDEX:{
 	if (insn == BIN(getlocal) || insn == BIN(setlocal)) {
 	    if (pnop) {
-		rb_iseq_t *diseq = iseq;
+		const rb_iseq_t *diseq = iseq;
 		VALUE level = *pnop, i;
 
 		for (i = 0; i < level; i++) {
@@ -1280,8 +1280,8 @@ rb_insn_operand_intern(rb_iseq_t *iseq,
  * Iseq -> Iseq inspect object
  */
 int
-rb_iseq_disasm_insn(VALUE ret, VALUE *iseq, size_t pos,
-		    rb_iseq_t *iseqdat, VALUE child)
+rb_iseq_disasm_insn(VALUE ret, const VALUE *iseq, size_t pos,
+		    const rb_iseq_t *iseqdat, VALUE child)
 {
     VALUE insn = iseq[pos];
     int len = insn_len(insn);
diff --git a/math.c b/math.c
index 78cba5ab0c..a09d605911 100644
--- a/math.c
+++ b/math.c
@@ -456,7 +456,7 @@ static double math_log1(VALUE x);
  */
 
 static VALUE
-math_log(int argc, VALUE *argv, VALUE obj)
+math_log(int argc, const VALUE *argv, VALUE obj)
 {
     VALUE x, base;
     double d;
@@ -918,7 +918,7 @@ exp1(exp)
 exp2(hypot)
 
 VALUE
-rb_math_log(int argc, VALUE *argv)
+rb_math_log(int argc, const VALUE *argv)
 {
     return math_log(argc, argv, rb_mMath);
 }
diff --git a/proc.c b/proc.c
index 8153cc9cfd..48aaf863e6 100644
--- a/proc.c
+++ b/proc.c
@@ -1873,14 +1873,14 @@ method_clone(VALUE self)
  */
 
 VALUE
-rb_method_call(int argc, VALUE *argv, VALUE method)
+rb_method_call(int argc, const VALUE *argv, VALUE method)
 {
     VALUE proc = rb_block_given_p() ? rb_block_proc() : Qnil;
     return rb_method_call_with_block(argc, argv, method, proc);
 }
 
 VALUE
-rb_method_call_with_block(int argc, VALUE *argv, VALUE method, VALUE pass_procval)
+rb_method_call_with_block(int argc, const VALUE *argv, VALUE method, VALUE pass_procval)
 {
     VALUE result = Qnil;	/* OK */
     struct METHOD *data;
diff --git a/process.c b/process.c
index bf9f42b909..cd498fe3cd 100644
--- a/process.c
+++ b/process.c
@@ -2435,7 +2435,7 @@ static int rb_exec_without_timer_thread(const struct rb_execarg *eargp, char *er
  */
 
 VALUE
-rb_f_exec(int argc, VALUE *argv)
+rb_f_exec(int argc, const VALUE *argv)
 {
     VALUE execarg_obj, fail_str;
     struct rb_execarg *eargp;
@@ -3585,7 +3585,7 @@ rb_exit(int status)
  */
 
 VALUE
-rb_f_exit(int argc, VALUE *argv)
+rb_f_exit(int argc, const VALUE *argv)
 {
     VALUE status;
     int istatus;
@@ -3614,8 +3614,9 @@ rb_f_exit(int argc, VALUE *argv)
  */
 
 VALUE
-rb_f_abort(int argc, VALUE *argv)
+rb_f_abort(int argc, const VALUE *argv)
 {
+    rb_check_arity(argc, 0, 1);
     if (argc == 0) {
 	if (!NIL_P(GET_THREAD()->errinfo)) {
 	    ruby_error_print();
@@ -3625,9 +3626,9 @@ rb_f_abort(int argc, VALUE *argv)
     else {
 	VALUE args[2];
 
-	rb_scan_args(argc, argv, "1", &args[1]);
-	StringValue(argv[0]);
-	rb_io_puts(argc, argv, rb_stderr);
+	args[1] = args[0] = argv[0];
+	StringValue(args[0]);
+	rb_io_puts(1, args, rb_stderr);
 	args[0] = INT2NUM(EXIT_FAILURE);
 	rb_exc_raise(rb_class_new_instance(2, args, rb_eSystemExit));
     }
@@ -3694,7 +3695,7 @@ rb_spawn_process(struct rb_execarg *eargp, char *errmsg, size_t errmsg_buflen)
 }
 
 static rb_pid_t
-rb_spawn_internal(int argc, VALUE *argv, char *errmsg, size_t errmsg_buflen)
+rb_spawn_internal(int argc, const VALUE *argv, char *errmsg, size_t errmsg_buflen)
 {
     VALUE execarg_obj;
     struct rb_execarg *eargp;
@@ -3709,13 +3710,13 @@ rb_spawn_internal(int argc, VALUE *argv, char *errmsg, size_t errmsg_buflen)
 }
 
 rb_pid_t
-rb_spawn_err(int argc, VALUE *argv, char *errmsg, size_t errmsg_buflen)
+rb_spawn_err(int argc, const VALUE *argv, char *errmsg, size_t errmsg_buflen)
 {
     return rb_spawn_internal(argc, argv, errmsg, errmsg_buflen);
 }
 
 rb_pid_t
-rb_spawn(int argc, VALUE *argv)
+rb_spawn(int argc, const VALUE *argv)
 {
     return rb_spawn_internal(argc, argv, NULL, 0);
 }
diff --git a/signal.c b/signal.c
index 75908420ef..fba6354c6e 100644
--- a/signal.c
+++ b/signal.c
@@ -388,7 +388,7 @@ static void signal_enque(int sig);
  */
 
 VALUE
-rb_f_kill(int argc, VALUE *argv)
+rb_f_kill(int argc, const VALUE *argv)
 {
 #ifndef HAVE_KILLPG
 #define killpg(pg, sig) kill(-(pg), (sig))
diff --git a/variable.c b/variable.c
index 265633f40c..dac12aba9e 100644
--- a/variable.c
+++ b/variable.c
@@ -607,9 +607,9 @@ rb_define_variable(const char *name, VALUE *var)
 }
 
 void
-rb_define_readonly_variable(const char *name, VALUE *var)
+rb_define_readonly_variable(const char *name, const VALUE *var)
 {
-    rb_define_hooked_variable(name, var, 0, readonly_setter);
+    rb_define_hooked_variable(name, (VALUE *)var, 0, readonly_setter);
 }
 
 void
@@ -653,7 +653,7 @@ rb_trace_eval(VALUE cmd, VALUE val)
  */
 
 VALUE
-rb_f_trace_var(int argc, VALUE *argv)
+rb_f_trace_var(int argc, const VALUE *argv)
 {
     VALUE var, cmd;
     struct global_entry *entry;
@@ -712,7 +712,7 @@ remove_trace(struct global_variable *var)
  */
 
 VALUE
-rb_f_untrace_var(int argc, VALUE *argv)
+rb_f_untrace_var(int argc, const VALUE *argv)
 {
     VALUE var, cmd;
     ID id;
@@ -2066,7 +2066,7 @@ rb_const_list(void *data)
  */
 
 VALUE
-rb_mod_constants(int argc, VALUE *argv, VALUE mod)
+rb_mod_constants(int argc, const VALUE *argv, VALUE mod)
 {
     VALUE inherit;
 
@@ -2240,7 +2240,7 @@ rb_define_global_const(const char *name, VALUE val)
 }
 
 static void
-set_const_visibility(VALUE mod, int argc, VALUE *argv, rb_const_flag_t flag)
+set_const_visibility(VALUE mod, int argc, const VALUE *argv, rb_const_flag_t flag)
 {
     int i;
     st_data_t v;
@@ -2286,7 +2286,7 @@ set_const_visibility(VALUE mod, int argc, VALUE *argv, rb_const_flag_t flag)
  */
 
 VALUE
-rb_mod_private_constant(int argc, VALUE *argv, VALUE obj)
+rb_mod_private_constant(int argc, const VALUE *argv, VALUE obj)
 {
     set_const_visibility(obj, argc, argv, CONST_PRIVATE);
     return obj;
@@ -2300,7 +2300,7 @@ rb_mod_private_constant(int argc, VALUE *argv, VALUE obj)
  */
 
 VALUE
-rb_mod_public_constant(int argc, VALUE *argv, VALUE obj)
+rb_mod_public_constant(int argc, const VALUE *argv, VALUE obj)
 {
     set_const_visibility(obj, argc, argv, CONST_PUBLIC);
     return obj;
@@ -2526,7 +2526,7 @@ cvar_list(void *data)
  */
 
 VALUE
-rb_mod_class_variables(int argc, VALUE *argv, VALUE mod)
+rb_mod_class_variables(int argc, const VALUE *argv, VALUE mod)
 {
     VALUE inherit;
     st_table *tbl;
diff --git a/vm_backtrace.c b/vm_backtrace.c
index 7c7478c868..7355a5f973 100644
--- a/vm_backtrace.c
+++ b/vm_backtrace.c
@@ -820,7 +820,7 @@ rb_make_backtrace(void)
 }
 
 static VALUE
-vm_backtrace_to_ary(rb_thread_t *th, int argc, VALUE *argv, int lev_default, int lev_plus, int to_str)
+vm_backtrace_to_ary(rb_thread_t *th, int argc, const VALUE *argv, int lev_default, int lev_plus, int to_str)
 {
     VALUE level, vn;
     long lev, n;
@@ -891,7 +891,7 @@ vm_backtrace_to_ary(rb_thread_t *th, int argc, VALUE *argv, int lev_default, int
 }
 
 static VALUE
-thread_backtrace_to_ary(int argc, VALUE *argv, VALUE thval, int to_str)
+thread_backtrace_to_ary(int argc, const VALUE *argv, VALUE thval, int to_str)
 {
     rb_thread_t *th;
     GetThreadPtr(thval, th);
@@ -903,13 +903,13 @@ thread_backtrace_to_ary(int argc, VALUE *argv, VALUE thval, int to_str)
 }
 
 VALUE
-rb_vm_thread_backtrace(int argc, VALUE *argv, VALUE thval)
+rb_vm_thread_backtrace(int argc, const VALUE *argv, VALUE thval)
 {
     return thread_backtrace_to_ary(argc, argv, thval, 1);
 }
 
 VALUE
-rb_vm_thread_backtrace_locations(int argc, VALUE *argv, VALUE thval)
+rb_vm_thread_backtrace_locations(int argc, const VALUE *argv, VALUE thval)
 {
     return thread_backtrace_to_ary(argc, argv, thval, 0);
 }
diff --git a/vm_core.h b/vm_core.h
index adcf8f8c0a..8d0a6fc150 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -677,7 +677,7 @@ VALUE rb_iseq_compile_on_base(VALUE src, VALUE file, VALUE line, rb_block_t *bas
 VALUE rb_iseq_compile_with_option(VALUE src, VALUE file, VALUE absolute_path, VALUE line, rb_block_t *base_block, VALUE opt);
 
 VALUE rb_iseq_disasm(VALUE self);
-int rb_iseq_disasm_insn(VALUE str, VALUE *iseqval, size_t pos, rb_iseq_t *iseq, VALUE child);
+int rb_iseq_disasm_insn(VALUE str, const VALUE *iseqval, size_t pos, const rb_iseq_t *iseq, VALUE child);
 const char *ruby_node_name(int node);
 
 RUBY_EXTERN VALUE rb_cISeq;
diff --git a/vm_eval.c b/vm_eval.c
index d0b2b1e37d..4ae9a1777a 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -729,7 +729,7 @@ method_missing(VALUE obj, ID id, int argc, const VALUE *argv, int call_status)
 }
 
 void
-rb_raise_method_missing(rb_thread_t *th, int argc, VALUE *argv,
+rb_raise_method_missing(rb_thread_t *th, int argc, const VALUE *argv,
 			VALUE obj, int call_status)
 {
     th->passed_block = 0;
@@ -1352,7 +1352,7 @@ eval_string(VALUE self, VALUE src, VALUE scope, VALUE file, int line)
  */
 
 VALUE
-rb_f_eval(int argc, VALUE *argv, VALUE self)
+rb_f_eval(int argc, const VALUE *argv, VALUE self)
 {
     VALUE src, scope, vfile, vline;
     VALUE file = Qundef;
@@ -1570,7 +1570,7 @@ eval_under(VALUE under, VALUE self, VALUE src, VALUE file, int line)
 }
 
 static VALUE
-specific_eval(int argc, VALUE *argv, VALUE klass, VALUE self)
+specific_eval(int argc, const VALUE *argv, VALUE klass, VALUE self)
 {
     if (rb_block_given_p()) {
 	rb_check_arity(argc, 0, 0);
@@ -1579,16 +1579,18 @@ specific_eval(int argc, VALUE *argv, VALUE klass, VALUE self)
     else {
 	VALUE file = Qundef;
 	int line = 1;
+	VALUE code;
 
 	rb_check_arity(argc, 1, 3);
-	SafeStringValue(argv[0]);
+	code = argv[0];
+	SafeStringValue(code);
 	if (argc > 2)
 	    line = NUM2INT(argv[2]);
 	if (argc > 1) {
 	    file = argv[1];
 	    if (!NIL_P(file)) StringValue(file);
 	}
-	return eval_under(klass, self, argv[0], file, line);
+	return eval_under(klass, self, code, file, line);
     }
 }
 
@@ -1626,7 +1628,7 @@ specific_eval(int argc, VALUE *argv, VALUE klass, VALUE self)
  */
 
 VALUE
-rb_obj_instance_eval(int argc, VALUE *argv, VALUE self)
+rb_obj_instance_eval(int argc, const VALUE *argv, VALUE self)
 {
     VALUE klass;
 
@@ -1658,7 +1660,7 @@ rb_obj_instance_eval(int argc, VALUE *argv, VALUE self)
  */
 
 VALUE
-rb_obj_instance_exec(int argc, VALUE *argv, VALUE self)
+rb_obj_instance_exec(int argc, const VALUE *argv, VALUE self)
 {
     VALUE klass;
 
@@ -1697,7 +1699,7 @@ rb_obj_instance_exec(int argc, VALUE *argv, VALUE self)
  */
 
 VALUE
-rb_mod_module_eval(int argc, VALUE *argv, VALUE mod)
+rb_mod_module_eval(int argc, const VALUE *argv, VALUE mod)
 {
     return specific_eval(argc, argv, mod, mod);
 }
@@ -1725,7 +1727,7 @@ rb_mod_module_eval(int argc, VALUE *argv, VALUE mod)
  */
 
 VALUE
-rb_mod_module_exec(int argc, VALUE *argv, VALUE mod)
+rb_mod_module_exec(int argc, const VALUE *argv, VALUE mod)
 {
     return yield_under(mod, mod, rb_ary_new4(argc, argv));
 }
diff --git a/vm_method.c b/vm_method.c
index bb1b129544..966fc419b6 100644
--- a/vm_method.c
+++ b/vm_method.c
@@ -94,7 +94,7 @@ rb_clear_method_cache_by_class(VALUE klass)
 }
 
 VALUE
-rb_f_notimplement(int argc, VALUE *argv, VALUE obj)
+rb_f_notimplement(int argc, const VALUE *argv, VALUE obj)
 {
     rb_notimplement();
 
@@ -1336,7 +1336,7 @@ rb_mod_alias_method(VALUE mod, VALUE newname, VALUE oldname)
 }
 
 static void
-set_method_visibility(VALUE self, int argc, VALUE *argv, rb_method_flag_t ex)
+set_method_visibility(VALUE self, int argc, const VALUE *argv, rb_method_flag_t ex)
 {
     int i;
 
@@ -1357,7 +1357,7 @@ set_method_visibility(VALUE self, int argc, VALUE *argv, rb_method_flag_t ex)
 }
 
 static VALUE
-set_visibility(int argc, VALUE *argv, VALUE module, rb_method_flag_t ex)
+set_visibility(int argc, const VALUE *argv, VALUE module, rb_method_flag_t ex)
 {
     if (argc == 0) {
 	SCOPE_SET(ex);