diff --git a/README.rst b/README.rst
index 542d3753..427d42c0 100644
--- a/README.rst
+++ b/README.rst
@@ -37,6 +37,12 @@ ArrayKit requires the following:
 What is New in ArrayKit
 -------------------------
 
+0.9.0
+............
+
+Added ``TriMap.map_merge()``.
+
+
 0.8.3
 ............
 
diff --git a/setup.py b/setup.py
index 4317a50b..86f85ccd 100644
--- a/setup.py
+++ b/setup.py
@@ -5,7 +5,7 @@
 from setuptools import setup
 from pathlib import Path
 
-AK_VERSION = '0.8.3'
+AK_VERSION = '0.9.0'
 
 def get_long_description() -> str:
     return '''The ArrayKit library provides utilities for creating and transforming NumPy arrays, implementing performance-critical StaticFrame operations as Python C extensions.