diff --git a/src/header/locale/cbindgen.toml b/src/header/locale/cbindgen.toml
index f373d74a7e..9712e8ed37 100644
--- a/src/header/locale/cbindgen.toml
+++ b/src/header/locale/cbindgen.toml
@@ -1,3 +1,8 @@
+# POSIX header spec: https://pubs.opengroup.org/onlinepubs/9799919799/basedefs/locale.h.html
+#
+# Spec quotations relating to includes:
+# - "The <locale.h> header shall define NULL (as described in <stddef.h>) and at least the following as macros:"
+sys_includes = ["stddef.h"]
 include_guard = "_RELIBC_LOCALE_H"
 after_includes = """
 #include <bits/locale-t.h> // for locale_t
diff --git a/src/header/locale/mod.rs b/src/header/locale/mod.rs
index 0b55974077..948fbc92c4 100644
--- a/src/header/locale/mod.rs
+++ b/src/header/locale/mod.rs
@@ -15,7 +15,6 @@ use crate::{
     sync::Once,
 };
 
-const EMPTY_PTR: *const c_char = "\0" as *const _ as *const c_char;
 // Can't use &str because of the mutability
 static mut C_LOCALE: [c_char; 2] = [b'C' as c_char, 0];