diff --git a/gen/README.md b/gen/README.md
index 9786911b2..50adeca88 100644
--- a/gen/README.md
+++ b/gen/README.md
@@ -2,3 +2,6 @@ This directory contains CXX's C++ code generator. This code generator has two
 public frontends, one a command-line application (binary) in the *cmd* directory
 and the other a library intended to be used from a build.rs in the *build*
 directory.
+
+There's also a 'lib' frontend which is intended to allow higher level code generators
+to embed cxx. This is not yet recommended for general use.
diff --git a/gen/lib/src/lib.rs b/gen/lib/src/lib.rs
index dae7e7869..ecfa4361a 100644
--- a/gen/lib/src/lib.rs
+++ b/gen/lib/src/lib.rs
@@ -20,6 +20,7 @@ mod gen;
 mod syntax;
 
 pub use crate::error::Error;
+pub use crate::gen::include::HEADER;
 pub use crate::gen::{GeneratedCode, Opt};
 use proc_macro2::TokenStream;
 
diff --git a/gen/src/include.rs b/gen/src/include.rs
index 1688a4e3d..3255902ad 100644
--- a/gen/src/include.rs
+++ b/gen/src/include.rs
@@ -1,6 +1,7 @@
 use crate::gen::out::OutFile;
 use std::fmt::{self, Display};
 
+/// The complete contents of the "rust/cxx.h" header.
 pub static HEADER: &str = include_str!("include/cxx.h");
 
 pub(super) fn write(out: &mut OutFile, needed: bool, guard: &str) {