diff --git a/lib/std/c.zig b/lib/std/c.zig
index 2aeb30c875..fe9fc7ac40 100644
--- a/lib/std/c.zig
+++ b/lib/std/c.zig
@@ -132,6 +132,7 @@ pub extern "c" fn tcgetattr(fd: fd_t, termios_p: *termios) c_int;
 pub extern "c" fn tcsetattr(fd: fd_t, optional_action: TCSA, termios_p: *const termios) c_int;
 pub extern "c" fn fcntl(fd: fd_t, cmd: c_int, ...) c_int;
 pub extern "c" fn flock(fd: fd_t, operation: c_int) c_int;
+pub extern "c" fn ioctl(fd: fd_t, request: c_int, ...) c_int;
 pub extern "c" fn uname(buf: *utsname) c_int;
 
 pub extern "c" fn gethostname(name: [*]u8, len: usize) c_int;