diff --git a/lib/std/c/darwin.zig b/lib/std/c/darwin.zig
index d5ecf6bd81..881e52c72c 100644
--- a/lib/std/c/darwin.zig
+++ b/lib/std/c/darwin.zig
@@ -56,9 +56,9 @@ pub extern "c" fn host_get_clock_service(host: host_t, clock_id: clock_id_t, clo
 pub extern "c" fn mach_port_deallocate(task: ipc_space_t, name: mach_port_name_t) kern_return_t;
 
 pub const sf_hdtr = extern struct {
-    headers: [*]iovec_const,
+    headers: [*]const iovec_const,
     hdr_cnt: c_int,
-    trailers: [*]iovec_const,
+    trailers: [*]const iovec_const,
     trl_cnt: c_int,
 };
 
diff --git a/lib/std/c/freebsd.zig b/lib/std/c/freebsd.zig
index dacfa4384d..2c4820bbe9 100644
--- a/lib/std/c/freebsd.zig
+++ b/lib/std/c/freebsd.zig
@@ -9,9 +9,9 @@ pub extern "c" fn sigaltstack(ss: ?*stack_t, old_ss: ?*stack_t) c_int;
 pub extern "c" fn getrandom(buf_ptr: [*]u8, buf_len: usize, flags: c_uint) isize;
 
 pub const sf_hdtr = extern struct {
-    headers: [*]iovec_const,
+    headers: [*]const iovec_const,
     hdr_cnt: c_int,
-    trailers: [*]iovec_const,
+    trailers: [*]const iovec_const,
     trl_cnt: c_int,
 };
 pub extern "c" fn sendfile(
diff --git a/lib/std/os/bits/darwin.zig b/lib/std/os/bits/darwin.zig
index 22897974c2..fb933c6698 100644
--- a/lib/std/os/bits/darwin.zig
+++ b/lib/std/os/bits/darwin.zig
@@ -926,6 +926,9 @@ pub const ESOCKTNOSUPPORT = 44;
 /// Operation not supported
 pub const ENOTSUP = 45;
 
+/// Operation not supported. Alias of `ENOTSUP`.
+pub const EOPNOTSUPP = ENOTSUP;
+
 /// Protocol family not supported
 pub const EPFNOSUPPORT = 46;