diff --git a/CHANGELOG.md b/CHANGELOG.md
index d7ed0b6a..8edf5d94 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,28 @@
 
 All notable changes to this project will be documented in this file, in reverse chronological order by release.
 
+## 4.3.0 - 2020-04-01
+
+### Added
+
+- Nothing.
+
+### Changed
+
+- [#175](https://github.com/scoutapp/scout-apm-php/pull/175) Upgraded core-agent version to 1.2.9
+
+### Deprecated
+
+- Nothing.
+
+### Removed
+
+- Nothing.
+
+### Fixed
+
+- Nothing.
+
 ## 4.2.0 - 2020-03-17
 
 ### Added
diff --git a/src/Config/Source/DefaultSource.php b/src/Config/Source/DefaultSource.php
index f0951199..6c52aba8 100644
--- a/src/Config/Source/DefaultSource.php
+++ b/src/Config/Source/DefaultSource.php
@@ -50,7 +50,7 @@ private function getDefaultConfig() : array
             ConfigKey::CORE_AGENT_DIRECTORY => '/tmp/scout_apm_core',
             ConfigKey::CORE_AGENT_DOWNLOAD_ENABLED => true,
             ConfigKey::CORE_AGENT_LAUNCH_ENABLED => true,
-            ConfigKey::CORE_AGENT_VERSION => 'v1.2.8',
+            ConfigKey::CORE_AGENT_VERSION => 'v1.2.9',
             ConfigKey::CORE_AGENT_DOWNLOAD_URL => 'https://s3-us-west-1.amazonaws.com/scout-public-downloads/apm_core_agent/release',
             ConfigKey::CORE_AGENT_PERMISSIONS => 0777,
             ConfigKey::MONITORING_ENABLED => false,