diff --git a/src/cloudabi/mod.rs b/src/cloudabi/mod.rs
index 89bd99f28d7406187c182f25a56e1daacd7da670..bb4b9fa301f8937b7d0663fb7905be67dd56aa46 100644
--- a/src/cloudabi/mod.rs
+++ b/src/cloudabi/mod.rs
@@ -55,6 +55,7 @@ s! {
     }
 }
 
+pub const _SC_NPROCESSORS_ONLN: ::c_int = 52;
 pub const _SC_PAGESIZE: ::c_int = 54;
 
 pub const AF_INET: ::c_int = 1;