Release 0.4.0
diff --git a/src/lib.rs b/src/lib.rs
index bbd79f3..1e76581 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -228,7 +228,7 @@
 //! # Cargo.toml
 //!
 //! [build-dependencies]
-//! cxx-build = "0.3"
+//! cxx-build = "0.4"
 //! ```
 //!
 //! ```no_run
@@ -348,7 +348,7 @@
 //!
 //! [https://github.com/dtolnay/cxx]: https://github.com/dtolnay/cxx
 
-#![doc(html_root_url = "https://docs.rs/cxx/0.3.9")]
+#![doc(html_root_url = "https://docs.rs/cxx/0.4.0")]
 #![deny(improper_ctypes)]
 #![allow(non_camel_case_types)]
 #![allow(