diff --git a/std/c/index.zig b/std/c/index.zig
index e6ba1b01fa..9e33ed2196 100644
--- a/std/c/index.zig
+++ b/std/c/index.zig
@@ -41,3 +41,5 @@ pub extern "c" fn realpath(noalias file_name: &const u8, noalias resolved_name:
 pub extern "c" fn sigprocmask(how: c_int, noalias set: &const sigset_t, noalias oset: ?&sigset_t) -> c_int;
 pub extern "c" fn sigaction(sig: c_int, noalias act: &const Sigaction, noalias oact: ?&Sigaction) -> c_int;
 pub extern "c" fn nanosleep(rqtp: &const timespec, rmtp: ?&timespec) -> c_int;
+pub extern "c" fn setreuid(ruid: c_uint, euid: c_uint) -> c_int;
+pub extern "c" fn setregid(rgid: c_uint, egid: c_uint) -> c_int;
diff --git a/std/os/darwin.zig b/std/os/darwin.zig
index 0cec438e5f..149523b069 100644
--- a/std/os/darwin.zig
+++ b/std/os/darwin.zig
@@ -229,6 +229,14 @@ pub fn realpath(noalias filename: &const u8, noalias resolved_name: &u8) -> usiz
     if (c.realpath(filename, resolved_name) == null) @bitCast(usize, -isize(*c._errno())) else 0
 }
 
+pub fn setreuid(ruid: u32, euid: u32) -> usize {
+    errnoWrap(c.setreuid(ruid, euid))
+}
+
+pub fn setregid(rgid: u32, egid: u32) -> usize {
+    errnoWrap(c.setregid(rgid, egid))
+}
+
 pub fn sigprocmask(flags: u32, noalias set: &const sigset_t, noalias oldset: ?&sigset_t) -> usize {
     errnoWrap(c.sigprocmask(@bitCast(c_int, flags), set, oldset))
 }