diff --git a/src/flag.rs b/src/flag.rs
index f4e7a6e..c519d0c 100644
--- a/src/flag.rs
+++ b/src/flag.rs
@@ -4,6 +4,7 @@ pub const CLONE_FILES: usize = 0x400;
 pub const CLONE_SIGHAND: usize = 0x800;
 pub const CLONE_VFORK: usize = 0x4000;
 pub const CLONE_THREAD: usize = 0x10000;
+pub const CLONE_STACK: usize = 0x1000_0000;
 
 pub const CLOCK_REALTIME: usize = 1;
 pub const CLOCK_MONOTONIC: usize = 4;