diff --git a/CHANGELOG.md b/CHANGELOG.md
index e31c836..9911b02 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,10 +1,10 @@
 # Changelog
 
-## Unreleased
+## v0.4.0 - 2021-11-30
 
 - The `erlang` module gains the `ensure_all_started` function.
 
-## v0.3.0 - 2021-11-23
+## v0.3.0 - 2021-11-30
 
 - The `erlang` module gains the `start_arguments` function.
 
diff --git a/gleam.toml b/gleam.toml
index 30d46b4..d72fdc0 100644
--- a/gleam.toml
+++ b/gleam.toml
@@ -1,6 +1,6 @@
 name = "gleam_erlang"
 
-version = "0.3.0"
+version = "0.4.0"
 licences = ["Apache-2.0"]
 description = "A Gleam library for working with Erlang"