diff --git a/include/sys/mman.h b/include/sys/mman.h
index 596a03a70ce7ecf7c6e77ed6027975614ef98ed0..8a5149c980b3754e76fdb11dc0aaf720b1a95e63 100644
--- a/include/sys/mman.h
+++ b/include/sys/mman.h
@@ -62,6 +62,7 @@ extern "C" {
 #define MADV_SEQUENTIAL  2
 #define MADV_WILLNEED    3
 #define MADV_DONTNEED    4
+#define MADV_FREE        8
 #define MADV_REMOVE      9
 #define MADV_DONTFORK    10
 #define MADV_DOFORK      11