diff --git a/CHANGELOG.md b/CHANGELOG.md
index 109451db5d778..e8d8db5a1e036 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,7 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [0.4.0] - 2023-09-04
 
 #### Added
  - New module `ellswift` implements ElligatorSwift encoding for public keys and x-only Diffie-Hellman key exchange for them.
@@ -21,6 +21,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 #### Changed
  - When consuming libsecp256k1 as a static library on Windows, the user must now define the `SECP256K1_STATIC` macro before including `secp256k1.h`.
 
+#### ABI Compatibility
+This release is backward compatible with the ABI of 0.3.0, 0.3.1, and 0.3.2. Symbol visibility is now believed to be handled properly on supported platforms and is now considered to be part of the ABI. Please report any improperly exported symbols as a bug.
+
 ## [0.3.2] - 2023-05-13
 We strongly recommend updating to 0.3.2 if you use or plan to use GCC >=13 to compile libsecp256k1. When in doubt, check the GCC version using `gcc -v`.
 
@@ -101,7 +104,8 @@ This version was in fact never released.
 The number was given by the build system since the introduction of autotools in Jan 2014 (ea0fe5a5bf0c04f9cc955b2966b614f5f378c6f6).
 Therefore, this version number does not uniquely identify a set of source files.
 
-[unreleased]: https://github.com/bitcoin-core/secp256k1/compare/v0.3.2...HEAD
+[unreleased]: https://github.com/bitcoin-core/secp256k1/compare/v0.4.0...HEAD
+[0.4.0]: https://github.com/bitcoin-core/secp256k1/compare/v0.3.2...v0.4.0
 [0.3.2]: https://github.com/bitcoin-core/secp256k1/compare/v0.3.1...v0.3.2
 [0.3.1]: https://github.com/bitcoin-core/secp256k1/compare/v0.3.0...v0.3.1
 [0.3.0]: https://github.com/bitcoin-core/secp256k1/compare/v0.2.0...v0.3.0
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3107eb3bf1666..cdac47ba9d1cf 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,7 +11,7 @@ project(libsecp256k1
   # The package (a.k.a. release) version is based on semantic versioning 2.0.0 of
   # the API. All changes in experimental modules are treated as
   # backwards-compatible and therefore at most increase the minor version.
-  VERSION 0.3.3
+  VERSION 0.4.0
   DESCRIPTION "Optimized C library for ECDSA signatures and secret/public key operations on curve secp256k1."
   HOMEPAGE_URL "https://github.com/bitcoin-core/secp256k1"
   LANGUAGES C
@@ -34,9 +34,9 @@ endif()
 # https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
 # All changes in experimental modules are treated as if they don't affect the
 # interface and therefore only increase the revision.
-set(${PROJECT_NAME}_LIB_VERSION_CURRENT 2)
-set(${PROJECT_NAME}_LIB_VERSION_REVISION 3)
-set(${PROJECT_NAME}_LIB_VERSION_AGE 0)
+set(${PROJECT_NAME}_LIB_VERSION_CURRENT 3)
+set(${PROJECT_NAME}_LIB_VERSION_REVISION 0)
+set(${PROJECT_NAME}_LIB_VERSION_AGE 1)
 
 set(CMAKE_C_STANDARD 90)
 set(CMAKE_C_EXTENSIONS OFF)
diff --git a/configure.ac b/configure.ac
index 187849672482a..e3877850d3cfb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -4,18 +4,18 @@ AC_PREREQ([2.60])
 # the API. All changes in experimental modules are treated as
 # backwards-compatible and therefore at most increase the minor version.
 define(_PKG_VERSION_MAJOR, 0)
-define(_PKG_VERSION_MINOR, 3)
-define(_PKG_VERSION_PATCH, 3)
-define(_PKG_VERSION_IS_RELEASE, false)
+define(_PKG_VERSION_MINOR, 4)
+define(_PKG_VERSION_PATCH, 0)
+define(_PKG_VERSION_IS_RELEASE, true)
 
 # The library version is based on libtool versioning of the ABI. The set of
 # rules for updating the version can be found here:
 # https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html
 # All changes in experimental modules are treated as if they don't affect the
 # interface and therefore only increase the revision.
-define(_LIB_VERSION_CURRENT, 2)
-define(_LIB_VERSION_REVISION, 3)
-define(_LIB_VERSION_AGE, 0)
+define(_LIB_VERSION_CURRENT, 3)
+define(_LIB_VERSION_REVISION, 0)
+define(_LIB_VERSION_AGE, 1)
 
 AC_INIT([libsecp256k1],m4_join([.], _PKG_VERSION_MAJOR, _PKG_VERSION_MINOR, _PKG_VERSION_PATCH)m4_if(_PKG_VERSION_IS_RELEASE, [true], [], [-dev]),[https://github.com/bitcoin-core/secp256k1/issues],[libsecp256k1],[https://github.com/bitcoin-core/secp256k1])