diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4b30380..66e04da 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,15 @@
+# v0.4.0
+## Features
+- Overhauled the `unit_system` macro. (see the readme and the SI module in `src/si.rs` for example usage). (See #44)
+- - The `Dimension` type does not need to be defined by the user anymore and is derived automatically.
+- - The new syntax is much more explicit about what the base units are and prevents accidentally declaring multiple base units (which could be a critical error). 
+- - Similarly, defining units in terms of a dimension is not allowed anymore and units can only be derived from the base units and other derived units.
+- - Support adding prefixes to custom units via the `#[prefix(...)]` attribute to save time and prevent bugs due to typos due to wrong conversion factors.
+- - Support adding aliases to custom units via the `#[alias(...)]` attribute.
+- - Added a large list of dimensions and units to the SI module, each including all metric prefixes from atto to exa.
+- Add support for rational dimensions. This is not enabled by default and requires the `rational-dimensions` feature gate. (See #48)
+- Add various numeric trait implementations for references of quantities. (See #50 and #53)
+
 # v0.3.0
 ## Features
 - Add various trait implementations for dimensionless quantities and their underlying storage types: `MulAssign`, `DivAssign` , `PartialEq`, `PartialOrd`, `From`. For example, this makes it possible to write:
diff --git a/Cargo.toml b/Cargo.toml
index 832cebe..8ec10ce 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "diman"
-version = "0.3.0"
+version = "0.4.0"
 edition = "2021"
 description = "Zero-cost compile-time dimensional analysis."
 authors = ["Toni Peter <mail@tonipeter.de>"]
@@ -41,7 +41,7 @@ hdf5 = { version = "0.8.1", optional = true }
 mpi = { version = "0.7", default-features = false, features = ["derive"], optional = true }
 once_cell = { version = "1.18.0", optional = true }
 
-diman_unit_system = { path = "crates/diman_unit_system", version = "0.3" }
+diman_unit_system = { path = "crates/diman_unit_system", version = "0.4" }
 
 [dev-dependencies]
 serde_yaml = "0.9.27"
diff --git a/crates/diman_unit_system/Cargo.toml b/crates/diman_unit_system/Cargo.toml
index 2aa7a88..2651ada 100644
--- a/crates/diman_unit_system/Cargo.toml
+++ b/crates/diman_unit_system/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "diman_unit_system"
-version = "0.3.0"
+version = "0.4.0"
 edition = "2021"
 authors = [
     "Toni Peter <mail@tonipeter.de>",