diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7bf539c5..b7ac3471 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## [Unreleased]
 
+## [4.0]
+
 * Add late move reductions (100.80 +- 22.10 Elo)
 * Use SEE to order bad captures later in moves to try (6.69 +- 4.80 Elo)
 * Do not allow TT cutoffs in PV nodes (~0 Elo)
@@ -183,7 +185,8 @@ Initial release with the following major features:
     * Tapered midgame vs. endgame evaluation
     * Incremental updates
 
-[unreleased]: https://github.com/jgilchrist/chess-engine/compare/v3.0...HEAD
+[unreleased]: https://github.com/jgilchrist/chess-engine/compare/v4.0...HEAD
+[4.0]: https://github.com/jgilchrist/chess-engine/compare/v3.0..v4.0
 [3.0]: https://github.com/jgilchrist/chess-engine/compare/v2.5..v3.0
 [2.5]: https://github.com/jgilchrist/chess-engine/compare/v2.4..v2.5
 [2.4]: https://github.com/jgilchrist/chess-engine/compare/v2.3..v2.4
diff --git a/Cargo.lock b/Cargo.lock
index a18b0ee4..06610c89 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -20,7 +20,7 @@ dependencies = [
 
 [[package]]
 name = "engine"
-version = "3.0.0"
+version = "4.0.0"
 dependencies = [
  "colored",
  "nom",
diff --git a/Cargo.toml b/Cargo.toml
index 88eac088..7fe9f972 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "engine"
-version = "3.0.0"
+version = "4.0.0"
 edition = "2021"
 rust-version = "1.81"