diff --git a/.github/workflows/python.yaml b/.github/workflows/python.yaml
index 835a4e4..8fd0cb9 100644
--- a/.github/workflows/python.yaml
+++ b/.github/workflows/python.yaml
@@ -8,7 +8,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11"]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
         os: [ubuntu-latest, windows-latest]
 
     steps:
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index bdc2c67..09225b2 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -6,6 +6,8 @@ Changelog
 ===========================
 - Lock pandas to 2.1.4 or later
 - Capital Investment result calculation fixed
+- Defults expansion moved to ReadStrategy
+- Adds Python 3.12 support
 
 Version 1.1.2
 =============
diff --git a/README.rst b/README.rst
index df34843..a34821a 100644
--- a/README.rst
+++ b/README.rst
@@ -14,7 +14,7 @@ otoole: OSeMOSYS tools for energy work
     :target: https://github.com/psf/black
     :alt: Code Style
 
-.. image:: https://img.shields.io/badge/python-3.9_|_3.10_|_3.11-blue.svg
+.. image:: https://img.shields.io/badge/python-3.9_|_3.10_|_3.11|_3.12-blue.svg
     :target: https://crate.io/packages/otoole/
     :alt: Python Version
 
diff --git a/src/otoole/input.py b/src/otoole/input.py
index e1082f7..d5a22e6 100644
--- a/src/otoole/input.py
+++ b/src/otoole/input.py
@@ -561,7 +561,12 @@ def _expand_dataframe(
 
         default_df = self._get_default_dataframe(name, input_data, default_values)
 
-        df = pd.concat([df, default_df])
+        # future warning of concating empty dataframe
+        if not df.empty:
+            df = pd.concat([df, default_df])
+        else:
+            df = default_df.copy()
+
         df = df[~df.index.duplicated(keep="first")]
 
         df = self._check_index_dtypes(name, self.user_config[name], df)