diff --git a/basis/unix/ffi/bsd/macosx/macosx.factor b/basis/unix/ffi/bsd/macosx/macosx.factor
index 2ca1d9315d..5a6775f214 100644
--- a/basis/unix/ffi/bsd/macosx/macosx.factor
+++ b/basis/unix/ffi/bsd/macosx/macosx.factor
@@ -5,6 +5,9 @@ IN: unix.ffi
 
 CONSTANT: FD_SETSIZE 1024
 
+CONSTANT: AF_INET6 30
+ALIAS: PF_INET6 AF_INET6
+
 STRUCT: addrinfo
     { flags int }
     { family int }