diff --git a/Cargo.toml b/Cargo.toml
index 18788a02ff..8b224f2c3f 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "redox_syscall"
-version = "0.5.16"
+version = "0.5.17"
 description = "A Rust library to access raw Redox system calls"
 license = "MIT"
 authors = ["Jeremy Soller <jackpot51@gmail.com>"]
diff --git a/src/flag.rs b/src/flag.rs
index 70b94a35a6..4098d96f10 100644
--- a/src/flag.rs
+++ b/src/flag.rs
@@ -401,3 +401,6 @@ bitflags! {
         const FD_UPPER = 1 << 14;
     }
 }
+
+/// The tag for the fd number in the upper file descriptor table.
+pub const UPPER_FDTBL_TAG: usize = 1 << (usize::BITS - 2);