diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11c5f83..3ca2a72 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,16 @@ All notable changes to this project are documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/), and this project
 adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [0.4.0] - 2026-07-30
+
+`numpy` is now the only runtime dependency, and a trained map can be saved without `pickle`.
+
+**Results change in two places.** Linear initialization is corrected for data far from the origin,
+where 0.3.0 was wrong by up to 5.8%; and anyone who imported pandas or scikit-learn transitively
+through this package must now depend on them directly. Everything else is additive: no public name or
+signature is removed, and `mode="batch"` and the other plain strings keep working.
+
+To reproduce a figure made with an earlier version, pin that version.
 
 ### Added
 
diff --git a/pyproject.toml b/pyproject.toml
index d9a2229..90ef970 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "python-som"
-version = "0.3.0"
+version = "0.4.0"
 authors = [{ name = "André Moreira Souza", email = "msouza.andre@hotmail.com" }]
 description = "Python implementation of the Self-Organizing Map"
 readme = "README.md"
diff --git a/src/python_som/_version.py b/src/python_som/_version.py
index 5e07a34..88d3b0c 100644
--- a/src/python_som/_version.py
+++ b/src/python_som/_version.py
@@ -9,4 +9,4 @@
 
 __all__ = ["__version__"]
 
-__version__ = "0.3.0"
+__version__ = "0.4.0"
diff --git a/uv.lock b/uv.lock
index 61d7020..574fdbe 100644
--- a/uv.lock
+++ b/uv.lock
@@ -2559,7 +2559,7 @@ wheels = [
 
 [[package]]
 name = "python-som"
-version = "0.3.0"
+version = "0.4.0"
 source = { editable = "." }
 dependencies = [
     { name = "numpy", version = "2.2.6", source = { registry = "https://pypi.org/simple" }, marker = "python_full_version < '3.11'" },