diff --git a/libc/include/ftw.h b/libc/include/ftw.h
index ebd59f5..ac901cc 100644
--- a/libc/include/ftw.h
+++ b/libc/include/ftw.h
@@ -54,9 +54,9 @@
 };
 
 __BEGIN_DECLS
-int ftw(const char*, int (*)(const char*, const struct stat*, int), int) __INTRODUCED_IN(21);
+int ftw(const char*, int (*)(const char*, const struct stat*, int), int) __INTRODUCED_IN(17);
 int nftw(const char*, int (*)(const char*, const struct stat*, int, struct FTW*), int, int)
-  __INTRODUCED_IN(21);
+  __INTRODUCED_IN(17);
 int ftw64(const char*, int (*)(const char*, const struct stat64*, int), int) __INTRODUCED_IN(21);
 int nftw64(const char*, int (*)(const char*, const struct stat64*, int, struct FTW*), int, int)
   __INTRODUCED_IN(21);