diff --git a/src/flag.rs b/src/flag.rs
index 747bf24..195ecb6 100644
--- a/src/flag.rs
+++ b/src/flag.rs
@@ -77,6 +77,7 @@ bitflags! {
 
         /// Only accepted for mmap2(2).
         const MAP_FIXED = 0x0004;
+        const MAP_FIXED_NOREPLACE = 0x000C;
     }
 }