diff --git a/src/libc.rs b/src/libc.rs
index 8e3af35e5..6269f0f7d 100644
--- a/src/libc.rs
+++ b/src/libc.rs
@@ -3,34 +3,6 @@ use std::sync::atomic::AtomicPtr;
 use libc::{c_char, c_int};
 use once_cell::sync::Lazy;
 
-pub fn MB_CUR_MAX() -> usize {
-    unsafe { C_MB_CUR_MAX() }
-}
-extern "C" {
-    fn C_MB_CUR_MAX() -> usize;
-}
-
-pub fn ST_LOCAL() -> u64 {
-    unsafe { C_ST_LOCAL() }
-}
-extern "C" {
-    fn C_ST_LOCAL() -> u64;
-}
-
-pub fn MNT_LOCAL() -> u64 {
-    unsafe { C_MNT_LOCAL() }
-}
-extern "C" {
-    fn C_MNT_LOCAL() -> u64;
-}
-
-pub fn _CS_PATH() -> i32 {
-    unsafe { C_CS_PATH() }
-}
-extern "C" {
-    fn C_CS_PATH() -> i32;
-}
-
 pub static _PATH_BSHELL: AtomicPtr<c_char> = AtomicPtr::new(std::ptr::null_mut());
 extern "C" {
     pub fn C_PATH_BSHELL() -> *const c_char;
@@ -54,11 +26,19 @@ extern "C" {
 macro_rules! CVAR {
     ($cfn:ident, $cvar:ident, $type:ident) => {
         pub fn $cvar() -> $type {
+            extern "C" {
+                fn $cfn() -> $type;
+            }
             unsafe { $cfn() }
         }
     };
 }
 
+CVAR!(C_MB_CUR_MAX, MB_CUR_MAX, usize);
+CVAR!(C_ST_LOCAL, ST_LOCAL, u64);
+CVAR!(C_MNT_LOCAL, MNT_LOCAL, u64);
+CVAR!(C_CS_PATH, _CS_PATH, i32);
+
 CVAR!(C_RLIMIT_SBSIZE, RLIMIT_SBSIZE, i32);
 CVAR!(C_RLIMIT_CORE, RLIMIT_CORE, i32);
 CVAR!(C_RLIMIT_DATA, RLIMIT_DATA, i32);
@@ -79,26 +59,3 @@ CVAR!(C_RLIMIT_RTTIME, RLIMIT_RTTIME, i32);
 CVAR!(C_RLIMIT_KQUEUES, RLIMIT_KQUEUES, i32);
 CVAR!(C_RLIMIT_NPTS, RLIMIT_NPTS, i32);
 CVAR!(C_RLIMIT_NTHR, RLIMIT_NTHR, i32);
-
-extern "C" {
-    fn C_RLIMIT_SBSIZE() -> i32; // ifndef: -1
-    fn C_RLIMIT_CORE() -> i32;
-    fn C_RLIMIT_DATA() -> i32;
-    fn C_RLIMIT_NICE() -> i32; // ifndef: -1
-    fn C_RLIMIT_FSIZE() -> i32;
-    fn C_RLIMIT_SIGPENDING() -> i32; // ifndef: -1
-    fn C_RLIMIT_MEMLOCK() -> i32; // ifndef: -1
-    fn C_RLIMIT_RSS() -> i32; // ifndef: -1
-    fn C_RLIMIT_NOFILE() -> i32;
-    fn C_RLIMIT_MSGQUEUE() -> i32; // ifndef: -1
-    fn C_RLIMIT_RTPRIO() -> i32; // ifndef: -1
-    fn C_RLIMIT_STACK() -> i32;
-    fn C_RLIMIT_CPU() -> i32;
-    fn C_RLIMIT_NPROC() -> i32; // ifndef: -1
-    fn C_RLIMIT_AS() -> i32; // ifndef: -1
-    fn C_RLIMIT_SWAP() -> i32; // ifndef: -1
-    fn C_RLIMIT_RTTIME() -> i32; // ifndef: -1
-    fn C_RLIMIT_KQUEUES() -> i32; // ifndef: -1
-    fn C_RLIMIT_NPTS() -> i32; // ifndef: -1
-    fn C_RLIMIT_NTHR() -> i32; // ifndef: -1
-}