diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index ea6c8a1..937a873 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -176,12 +176,12 @@
 extern off64_t lseek64(int __fd, off64_t __offset, int __whence);
 
 #if defined(__USE_FILE_OFFSET64) && __ANDROID_API__ >= 21
-extern int truncate(const char* __path, off_t __length) __RENAME(truncate64);
-extern ssize_t pread(int __fd, void* __buf, size_t __count, off_t __offset)
-  __RENAME(pread64);
-extern ssize_t pwrite(int __fd, const void* __buf, size_t __count,
-                      off_t __offset) __RENAME(pwrite64);
-extern int ftruncate(int __fd, off_t __length) __RENAME(ftruncate64);
+extern int truncate(const char* __path, off_t __length) __RENAME(truncate64) __INTRODUCED_IN(21);
+extern ssize_t pread(int __fd, void* __buf, size_t __count, off_t __offset) __RENAME(pread64)
+  __INTRODUCED_IN(12);
+extern ssize_t pwrite(int __fd, const void* __buf, size_t __count, off_t __offset)
+  __RENAME(pwrite64) __INTRODUCED_IN(12);
+extern int ftruncate(int __fd, off_t __length) __RENAME(ftruncate64) __INTRODUCED_IN(12);
 #else
 extern int truncate(const char* __path, off_t __length);
 extern ssize_t pread(int __fd, void* __buf, size_t __count, off_t __offset);
@@ -191,10 +191,10 @@
 #endif
 
 extern int truncate64(const char* __path, off64_t __length) __INTRODUCED_IN(21);
-extern ssize_t pread64(int __fd, void* __buf, size_t __count, off64_t __offset) __INTRODUCED_IN(21);
-extern ssize_t pwrite64(int __fd, const void* __buf, size_t __count,
-                        off64_t __offset) __INTRODUCED_IN(21);
-extern int ftruncate64(int __fd, off64_t __length) __INTRODUCED_IN(21);
+extern ssize_t pread64(int __fd, void* __buf, size_t __count, off64_t __offset) __INTRODUCED_IN(12);
+extern ssize_t pwrite64(int __fd, const void* __buf, size_t __count, off64_t __offset)
+  __INTRODUCED_IN(12);
+extern int ftruncate64(int __fd, off64_t __length) __INTRODUCED_IN(12);
 
 extern int pause(void);
 extern unsigned int alarm(unsigned int __seconds);
@@ -202,7 +202,7 @@
 extern int usleep(useconds_t __usec);
 
 int gethostname(char* __name, size_t __len);
-int sethostname(const char* __name, size_t __len);
+int sethostname(const char* __name, size_t __len) __INTRODUCED_IN(23);
 
 extern void* __brk(void* __addr);
 extern int brk(void* __addr);
@@ -243,52 +243,53 @@
     _rc; })
 
 /* TODO(unified-headers): Factor out all the FORTIFY features. */
-extern char* __getcwd_chk(char*, size_t, size_t);
+extern char* __getcwd_chk(char*, size_t, size_t) __INTRODUCED_IN(24);
 __errordecl(__getcwd_dest_size_error, "getcwd called with size bigger than destination");
 extern char* __getcwd_real(char*, size_t) __RENAME(getcwd);
 
-extern ssize_t __pread_chk(int, void*, size_t, off_t, size_t);
+extern ssize_t __pread_chk(int, void*, size_t, off_t, size_t) __INTRODUCED_IN(23);
 __errordecl(__pread_dest_size_error, "pread called with size bigger than destination");
 __errordecl(__pread_count_toobig_error, "pread called with count > SSIZE_MAX");
 extern ssize_t __pread_real(int, void*, size_t, off_t) __RENAME(pread);
 
-extern ssize_t __pread64_chk(int, void*, size_t, off64_t, size_t);
+extern ssize_t __pread64_chk(int, void*, size_t, off64_t, size_t) __INTRODUCED_IN(23);
 __errordecl(__pread64_dest_size_error, "pread64 called with size bigger than destination");
 __errordecl(__pread64_count_toobig_error, "pread64 called with count > SSIZE_MAX");
-extern ssize_t __pread64_real(int, void*, size_t, off64_t) __RENAME(pread64);
+extern ssize_t __pread64_real(int, void*, size_t, off64_t) __RENAME(pread64) __INTRODUCED_IN(12);
 
-extern ssize_t __pwrite_chk(int, const void*, size_t, off_t, size_t);
+extern ssize_t __pwrite_chk(int, const void*, size_t, off_t, size_t) __INTRODUCED_IN(24);
 __errordecl(__pwrite_dest_size_error, "pwrite called with size bigger than destination");
 __errordecl(__pwrite_count_toobig_error, "pwrite called with count > SSIZE_MAX");
 extern ssize_t __pwrite_real(int, const void*, size_t, off_t) __RENAME(pwrite);
 
-extern ssize_t __pwrite64_chk(int, const void*, size_t, off64_t, size_t);
+extern ssize_t __pwrite64_chk(int, const void*, size_t, off64_t, size_t) __INTRODUCED_IN(24);
 __errordecl(__pwrite64_dest_size_error, "pwrite64 called with size bigger than destination");
 __errordecl(__pwrite64_count_toobig_error, "pwrite64 called with count > SSIZE_MAX");
-extern ssize_t __pwrite64_real(int, const void*, size_t, off64_t) __RENAME(pwrite64);
+extern ssize_t __pwrite64_real(int, const void*, size_t, off64_t) __RENAME(pwrite64)
+  __INTRODUCED_IN(12);
 
-extern ssize_t __read_chk(int, void*, size_t, size_t);
+extern ssize_t __read_chk(int, void*, size_t, size_t) __INTRODUCED_IN(21);
 __errordecl(__read_dest_size_error, "read called with size bigger than destination");
 __errordecl(__read_count_toobig_error, "read called with count > SSIZE_MAX");
 extern ssize_t __read_real(int, void*, size_t) __RENAME(read);
 
-extern ssize_t __write_chk(int, const void*, size_t, size_t);
+extern ssize_t __write_chk(int, const void*, size_t, size_t) __INTRODUCED_IN(24);
 __errordecl(__write_dest_size_error, "write called with size bigger than destination");
 __errordecl(__write_count_toobig_error, "write called with count > SSIZE_MAX");
 extern ssize_t __write_real(int, const void*, size_t) __RENAME(write);
 
-extern ssize_t __readlink_chk(const char*, char*, size_t, size_t);
+extern ssize_t __readlink_chk(const char*, char*, size_t, size_t) __INTRODUCED_IN(23);
 __errordecl(__readlink_dest_size_error, "readlink called with size bigger than destination");
 __errordecl(__readlink_size_toobig_error, "readlink called with size > SSIZE_MAX");
 extern ssize_t __readlink_real(const char*, char*, size_t) __RENAME(readlink);
 
-extern ssize_t __readlinkat_chk(int dirfd, const char*, char*, size_t, size_t);
+extern ssize_t __readlinkat_chk(int dirfd, const char*, char*, size_t, size_t) __INTRODUCED_IN(23);
 __errordecl(__readlinkat_dest_size_error, "readlinkat called with size bigger than destination");
 __errordecl(__readlinkat_size_toobig_error, "readlinkat called with size > SSIZE_MAX");
 extern ssize_t __readlinkat_real(int dirfd, const char*, char*, size_t) __RENAME(readlinkat);
 
-extern int getdomainname(char*, size_t);
-extern int setdomainname(const char*, size_t);
+extern int getdomainname(char*, size_t) __INTRODUCED_IN(25);
+extern int setdomainname(const char*, size_t) __INTRODUCED_IN(25);
 
 #if defined(__BIONIC_FORTIFY)