diff --git a/libc/include/sys/timex.h b/libc/include/sys/timex.h
index fade5c3..f704ce8 100644
--- a/libc/include/sys/timex.h
+++ b/libc/include/sys/timex.h
@@ -35,8 +35,8 @@
 
 __BEGIN_DECLS
 
-int adjtimex(struct timex*);
-int clock_adjtime(clockid_t, struct timex*);
+int adjtimex(struct timex*) __INTRODUCED_IN(24);
+int clock_adjtime(clockid_t, struct timex*) __INTRODUCED_IN(24);
 
 __END_DECLS