diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5889f4d008ca3da6b5113eac6cfacb07be5d3732..232821e2e186c18f306f098e05cf25ea875b6498 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,8 @@ KleidiCV uses [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 This changelog aims to follow the guiding principles of
 [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## 0.4.0 - not yet released
+
 ## 0.3.0 - 2024-12-12
 
 ### Added
diff --git a/adapters/opencv/CMakeLists.txt b/adapters/opencv/CMakeLists.txt
index 66cc4725f1f081a393648e9f89a62ba98b57be7b..a53f754a0c7b70f730450b6ccdb4f03fb637eac1 100644
--- a/adapters/opencv/CMakeLists.txt
+++ b/adapters/opencv/CMakeLists.txt
@@ -7,7 +7,7 @@ include("${CMAKE_CURRENT_LIST_DIR}/../../kleidicv_thread/CMakeLists.txt")
 
 project("KleidiCV OpenCV HAL")
 
-set(KLEIDICV_HAL_VERSION "0.3.0" CACHE INTERNAL "")
+set(KLEIDICV_HAL_VERSION "0.4.0" CACHE INTERNAL "")
 set(KLEIDICV_HAL_LIBRARIES "kleidicv_hal" CACHE INTERNAL "")
 set(KLEIDICV_HAL_HEADERS "${CMAKE_CURRENT_LIST_DIR}/kleidicv_hal.h" CACHE INTERNAL "")
 set(KLEIDICV_HAL_INCLUDE_DIRS "$<TARGET_PROPERTY:kleidicv_thread,INCLUDE_DIRECTORIES>" CACHE INTERNAL "")