diff --git a/src/header/unistd/sysconf.rs b/src/header/unistd/sysconf.rs
index 23b4fc385e..94b8d4df35 100644
--- a/src/header/unistd/sysconf.rs
+++ b/src/header/unistd/sysconf.rs
@@ -20,6 +20,7 @@ pub const _SC_PAGE_SIZE: c_int = 30;
 // ...
 pub const _SC_RE_DUP_MAX: c_int = 44;
 
+pub const _SC_NPROCESSORS_CONF: c_int = 57;
 pub const _SC_NPROCESSORS_ONLN: c_int = 58;
 
 // ...
@@ -56,6 +57,7 @@ pub extern "C" fn sysconf(name: c_int) -> c_long {
         _SC_TTY_NAME_MAX => 32,
         _SC_SYMLOOP_MAX => -1,
         _SC_HOST_NAME_MAX => 64,
+        _SC_NPROCESSORS_CONF => 1,
         _SC_NPROCESSORS_ONLN => 1,
         _ => {
             platform::ERRNO.set(errno::EINVAL);