diff --git a/src/unix/bsd/freebsdlike/dragonfly/mod.rs b/src/unix/bsd/freebsdlike/dragonfly/mod.rs
index 565eb80c02a14..6e9bd07553d60 100644
--- a/src/unix/bsd/freebsdlike/dragonfly/mod.rs
+++ b/src/unix/bsd/freebsdlike/dragonfly/mod.rs
@@ -1348,7 +1348,7 @@ pub const MINCORE_SUPER: ::c_int = 0x20;
 
 const_fn! {
     {const} fn _CMSG_ALIGN(n: usize) -> usize {
-        (n + 3) & !3
+        (n + ::mem::size_of::<::c_long>()) & !::mem::size_of::<::c_long>()
     }
 }