diff --git a/libc/include/utmp.h b/libc/include/utmp.h
index c6f22a5..62e8d59 100644
--- a/libc/include/utmp.h
+++ b/libc/include/utmp.h
@@ -101,7 +101,7 @@
 struct utmp* getutent(void);
 void endutent(void);
 
-int login_tty(int);
+int login_tty(int) __INTRODUCED_IN(23);
 
 __END_DECLS