diff --git a/include/picrin.h b/include/picrin.h
index 22069652..6fbfec57 100644
--- a/include/picrin.h
+++ b/include/picrin.h
@@ -40,9 +40,9 @@ extern "C" {
 #include "xrope/xrope.h"
 
 #if __STDC_VERSION__ >= 201112L
-# define NORETURN _Noreturn
+# define noreturn _Noreturn
 #elif __GNUC__ || __clang__
-# define NORETURN __attribute__((noreturn))
+# define noreturn __attribute__((noreturn))
 #endif
 
 #define FALLTHROUGH ((void)0)
@@ -199,10 +199,10 @@ struct pic_lib *pic_find_library(pic_state *, pic_value);
 void pic_import(pic_state *, pic_value);
 void pic_export(pic_state *, pic_sym);
 
-NORETURN void pic_abort(pic_state *, const char *);
-NORETURN void pic_raise(pic_state *, struct pic_error *);
-NORETURN void pic_error(pic_state *, const char *); /* obsoleted */
-NORETURN void pic_errorf(pic_state *, const char *, ...);
+noreturn void pic_abort(pic_state *, const char *);
+noreturn void pic_raise(pic_state *, struct pic_error *);
+noreturn void pic_error(pic_state *, const char *); /* obsoleted */
+noreturn void pic_errorf(pic_state *, const char *, ...);
 void pic_warn(pic_state *, const char *);
 
 const char *pic_errmsg(pic_state *);
diff --git a/src/cont.c b/src/cont.c
index e9659423..a7052214 100644
--- a/src/cont.c
+++ b/src/cont.c
@@ -139,7 +139,7 @@ native_stack_extend(pic_state *pic, struct pic_cont *cont)
   restore_cont(pic, cont);
 }
 
-NORETURN static void
+noreturn static void
 restore_cont(pic_state *pic, struct pic_cont *cont)
 {
   char v;
@@ -197,7 +197,7 @@ walk_to_block(pic_state *pic, pic_block *here, pic_block *there)
   }
 }
 
-NORETURN static pic_value
+noreturn static pic_value
 cont_call(pic_state *pic)
 {
   struct pic_proc *proc;
diff --git a/src/error.c b/src/error.c
index 9e2fda30..42dedae1 100644
--- a/src/error.c
+++ b/src/error.c
@@ -19,7 +19,7 @@ pic_errmsg(pic_state *pic)
   return pic_str_cstr(pic->err->msg);
 }
 
-NORETURN static void
+noreturn static void
 raise(pic_state *pic, struct pic_error *e)
 {
   pic->err = e;
@@ -30,7 +30,7 @@ raise(pic_state *pic, struct pic_error *e)
   longjmp(*pic->jmp, 1);
 }
 
-NORETURN static void
+noreturn static void
 error(pic_state *pic, pic_str *msg, pic_value irrs)
 {
   struct pic_error *e;
@@ -138,7 +138,7 @@ pic_error_with_exception_handler(pic_state *pic)
   return v;
 }
 
-NORETURN static pic_value
+noreturn static pic_value
 pic_error_raise(pic_state *pic)
 {
   pic_value v;
@@ -164,7 +164,7 @@ pic_error_raise_continuable(pic_state *pic)
   return pic_raise_continuable(pic, obj);
 }
 
-NORETURN static pic_value
+noreturn static pic_value
 pic_error_error(pic_state *pic)
 {
   pic_str *str;