diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0d3e513ad8..9181018707 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -44,6 +44,8 @@ This project adheres to [Semantic Versioning](https://semver.org/).
   (#[1515](https://github.com/nix-rust/nix/pull/1515))
 - Added `MAP_EXCL` mmap flag for freebsd.
   (#[1525](https://github.com/nix-rust/nix/pull/1525))
+- Added `MAP_ALIGNED_SUPER` mmap flag for freebsd.
+  (#[1522](https://github.com/nix-rust/nix/pull/1522))
 
 ### Changed
 
diff --git a/src/sys/mman.rs b/src/sys/mman.rs
index e3c36208bf..a6fcdd5abe 100644
--- a/src/sys/mman.rs
+++ b/src/sys/mman.rs
@@ -140,6 +140,9 @@ libc_bitflags!{
         MAP_NOCACHE;
         #[cfg(any(target_os = "ios", target_os = "macos"))]
         MAP_JIT;
+        /// Allows to use large pages, underlying alignment based on size.
+        #[cfg(target_os = "freesd")]
+        MAP_ALIGNED_SUPER;
     }
 }