diff --git a/libc/include/fcntl.h b/libc/include/fcntl.h
index 013d72c..26d4f1c 100644
--- a/libc/include/fcntl.h
+++ b/libc/include/fcntl.h
@@ -64,36 +64,36 @@
 #define SYNC_FILE_RANGE_WAIT_AFTER 4
 
 extern int creat(const char*, mode_t);
-extern int creat64(const char*, mode_t);
+extern int creat64(const char*, mode_t) __INTRODUCED_IN(21);
 extern int openat(int, const char*, int, ...);
-extern int openat64(int, const char*, int, ...);
+extern int openat64(int, const char*, int, ...) __INTRODUCED_IN(21);
 extern int open(const char*, int, ...);
-extern int open64(const char*, int, ...);
-extern ssize_t splice(int, off64_t*, int, off64_t*, size_t, unsigned int);
-extern ssize_t tee(int, int, size_t, unsigned int);
-extern ssize_t vmsplice(int, const struct iovec*, size_t, unsigned int);
+extern int open64(const char*, int, ...) __INTRODUCED_IN(21);
+extern ssize_t splice(int, off64_t*, int, off64_t*, size_t, unsigned int) __INTRODUCED_IN(21);
+extern ssize_t tee(int, int, size_t, unsigned int) __INTRODUCED_IN(21);
+extern ssize_t vmsplice(int, const struct iovec*, size_t, unsigned int) __INTRODUCED_IN(21);
 
 #if defined(__USE_FILE_OFFSET64)
-extern int fallocate(int, int, off_t, off_t) __RENAME(fallocate64);
-extern int posix_fadvise(int, off_t, off_t, int) __RENAME(posix_fadvise64);
-extern int posix_fallocate(int, off_t, off_t) __RENAME(posix_fallocate);
+extern int fallocate(int, int, off_t, off_t) __RENAME(fallocate64) __INTRODUCED_IN(21);
+extern int posix_fadvise(int, off_t, off_t, int) __RENAME(posix_fadvise64) __INTRODUCED_IN(21);
+extern int posix_fallocate(int, off_t, off_t) __RENAME(posix_fallocate) __INTRODUCED_IN(21);
 #else
-extern int fallocate(int, int, off_t, off_t);
-extern int posix_fadvise(int, off_t, off_t, int);
-extern int posix_fallocate(int, off_t, off_t);
+extern int fallocate(int, int, off_t, off_t) __INTRODUCED_IN(21);
+extern int posix_fadvise(int, off_t, off_t, int) __INTRODUCED_IN(21);
+extern int posix_fallocate(int, off_t, off_t) __INTRODUCED_IN(21);
 #endif
-extern int fallocate64(int, int, off64_t, off64_t);
-extern int posix_fadvise64(int, off64_t, off64_t, int);
-extern int posix_fallocate64(int, off64_t, off64_t);
+extern int fallocate64(int, int, off64_t, off64_t) __INTRODUCED_IN(21);
+extern int posix_fadvise64(int, off64_t, off64_t, int) __INTRODUCED_IN(21);
+extern int posix_fallocate64(int, off64_t, off64_t) __INTRODUCED_IN(21);
 
 #if defined(__USE_GNU)
-ssize_t readahead(int, off64_t, size_t);
-int sync_file_range(int, off64_t, off64_t, unsigned int);
+ssize_t readahead(int, off64_t, size_t) __INTRODUCED_IN(21);
+int sync_file_range(int, off64_t, off64_t, unsigned int) __INTRODUCED_IN(25);
 #endif
 
-extern int __open_2(const char*, int);
+extern int __open_2(const char*, int) __INTRODUCED_IN(21);
 extern int __open_real(const char*, int, ...) __RENAME(open);
-extern int __openat_2(int, const char*, int);
+extern int __openat_2(int, const char*, int) __INTRODUCED_IN(21);
 extern int __openat_real(int, const char*, int, ...) __RENAME(openat);
 __errordecl(__creat_missing_mode, "called with O_CREAT, but missing mode");
 __errordecl(__creat_too_many_args, "too many arguments");