diff --git a/.github/workflows/python-app.yml b/.github/workflows/python-app.yml
index d29a9c2..10a1e7a 100644
--- a/.github/workflows/python-app.yml
+++ b/.github/workflows/python-app.yml
@@ -17,7 +17,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        python-version: ["3.10"]
+        python-version: ["3.9"]
 
     steps:
     - uses: actions/checkout@v2
diff --git a/HISTORY.rst b/HISTORY.rst
index c15d7c5..4f4dbb2 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -2,6 +2,12 @@
 History
 =======
 
+1.1.0 (2023-07-30)
+------------------
+
+* Downgrade to Python 3.9
+
+
 1.0.0 (2023-06-03)
 ------------------
 
diff --git a/README.rst b/README.rst
index fb1d1e7..9470b25 100644
--- a/README.rst
+++ b/README.rst
@@ -115,7 +115,7 @@ Installation
 
 3- Create a new environment for swolfpy::
 
-        conda create --name swolfpy python=3.10
+        conda create --name swolfpy python=3.9
 
 4- Activate the environment::
 
diff --git a/pyproject.toml b/pyproject.toml
index 8489585..aa7f100 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,7 +7,7 @@ name = "swolfpy_processmodels"
 dynamic = ["version", "readme", "dependencies"]
 description = "Life-Cylce Process Models for swolfpy (swolfpy_processmodels)."
 license = {text = "GNU GENERAL PUBLIC LICENSE V2"}
-requires-python = ">=3.10"
+requires-python = ">=3.9"
 authors = [
   {name = "Mojtaba Sardarmehni", email = "msardar2@alumni.ncsu.edu"},
 ]
@@ -27,7 +27,7 @@ classifiers = [
     'Intended Audience :: Science/Research',
     'License :: OSI Approved :: GNU General Public License v2 (GPLv2)',
     'Natural Language :: English',
-    'Programming Language :: Python :: 3.10',
+    'Programming Language :: Python :: 3.9',
     'Operating System :: MacOS :: MacOS X',
     'Operating System :: Microsoft :: Windows',
     'Topic :: Scientific/Engineering :: Information Analysis',
@@ -47,11 +47,10 @@ readme = {file = ["README.rst", "HISTORY.rst"]}
 dependencies = {file = "requirements.txt"}
 
 [tool.setuptools]
-packages = ["swolfpy_processmodels"]
 include-package-data = true
 
-[tool.setuptools.package-data]
-package_input_data = []
+[tool.setuptools.packages.find]
+include = ["swolfpy_processmodels*"]
 
 [tool.black]
 line-length = 100
diff --git a/swolfpy_processmodels/__init__.py b/swolfpy_processmodels/__init__.py
index 25ff893..0402f74 100644
--- a/swolfpy_processmodels/__init__.py
+++ b/swolfpy_processmodels/__init__.py
@@ -38,4 +38,4 @@
     "AnF",
 ]
 
-__version__ = "1.0.0"
+__version__ = "1.1.0"