diff --git a/src/unix/notbsd/mod.rs b/src/unix/notbsd/mod.rs
index 5920c4b6..0472c06b 100644
--- a/src/unix/notbsd/mod.rs
+++ b/src/unix/notbsd/mod.rs
@@ -342,6 +342,7 @@ pub const IP_TTL: ::c_int = 2;
 pub const IP_HDRINCL: ::c_int = 3;
 pub const IP_ADD_MEMBERSHIP: ::c_int = 35;
 pub const IP_DROP_MEMBERSHIP: ::c_int = 36;
+pub const IP_TRANSPARENT: ::c_int = 19;
 pub const IPV6_ADD_MEMBERSHIP: ::c_int = 20;
 pub const IPV6_DROP_MEMBERSHIP: ::c_int = 21;