diff --git a/lib/std/c.zig b/lib/std/c.zig
index 845061b2ce..cf31100a73 100644
--- a/lib/std/c.zig
+++ b/lib/std/c.zig
@@ -121,6 +121,7 @@ pub extern "c" fn getsockname(sockfd: fd_t, noalias addr: *sockaddr, noalias add
 pub extern "c" fn connect(sockfd: fd_t, sock_addr: *const sockaddr, addrlen: socklen_t) c_int;
 pub extern "c" fn accept4(sockfd: fd_t, addr: *sockaddr, addrlen: *socklen_t, flags: c_uint) c_int;
 pub extern "c" fn getsockopt(sockfd: fd_t, level: c_int, optname: c_int, optval: *c_void, optlen: *socklen_t) c_int;
+pub extern "c" fn setsockopt(sockfd: fd_t, level: c_int, optname: c_int, optval: *c_void, optlen: socklen_t) c_int;
 pub extern "c" fn send(sockfd: fd_t, buf: *const c_void, len: usize, flags: u32) isize;
 pub extern "c" fn sendto(
     sockfd: fd_t,