diff --git a/src/flag.rs b/src/flag.rs
index 4098d96f10..263edde005 100644
--- a/src/flag.rs
+++ b/src/flag.rs
@@ -55,6 +55,7 @@ pub const F_GETFD: usize = 1;
 pub const F_SETFD: usize = 2;
 pub const F_GETFL: usize = 3;
 pub const F_SETFL: usize = 4;
+pub const F_DUPFD_CLOEXEC: usize = 1030;
 
 pub const FUTEX_WAIT: usize = 0;
 pub const FUTEX_WAKE: usize = 1;