diff --git a/.bumpversion.cfg b/.bumpversion.cfg
index 75dc2508..802d9412 100644
--- a/.bumpversion.cfg
+++ b/.bumpversion.cfg
@@ -1,5 +1,5 @@
 [bumpversion]
-current_version = 3.4.20
+current_version = 3.4.21
 commit = True
 tag = True
 
diff --git a/.cookiecutterrc b/.cookiecutterrc
index 9b0bf9ab..84da4c81 100644
--- a/.cookiecutterrc
+++ b/.cookiecutterrc
@@ -54,7 +54,7 @@ default_context:
     sphinx_doctest: "no"
     sphinx_theme: "sphinx-py3doc-enhanced-theme"
     test_matrix_separate_coverage: "no"
-    version: 3.4.20
+    version: 3.4.21
     version_manager: "bump2version"
     website: "https://github.com/NREL"
     year_from: "2023"
diff --git a/README.rst b/README.rst
index 32968ed9..40aed708 100644
--- a/README.rst
+++ b/README.rst
@@ -47,9 +47,9 @@ Free software: `MIT license <LICENSE>`__
     :alt: Supported implementations
     :target: https://pypi.org/project/geophires-x
 
-.. |commits-since| image:: https://img.shields.io/github/commits-since/softwareengineerprogrammer/GEOPHIRES-X/v3.4.20.svg
+.. |commits-since| image:: https://img.shields.io/github/commits-since/softwareengineerprogrammer/GEOPHIRES-X/v3.4.21.svg
     :alt: Commits since latest release
-    :target: https://github.com/softwareengineerprogrammer/GEOPHIRES-X/compare/v3.4.20...main
+    :target: https://github.com/softwareengineerprogrammer/GEOPHIRES-X/compare/v3.4.21...main
 
 .. |docs| image:: https://readthedocs.org/projects/GEOPHIRES-X/badge/?style=flat
     :target: https://nrel.github.io/GEOPHIRES-X
diff --git a/docs/conf.py b/docs/conf.py
index 62ee0b31..b28c68c8 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -18,7 +18,7 @@
 year = '2023'
 author = 'NREL'
 copyright = f'{year}, {author}'
-version = release = '3.4.20'
+version = release = '3.4.21'
 
 pygments_style = 'trac'
 templates_path = ['./templates']
diff --git a/setup.py b/setup.py
index 84c7bf00..7852222f 100755
--- a/setup.py
+++ b/setup.py
@@ -13,7 +13,7 @@ def read(*names, **kwargs):
 
 setup(
     name='geophires-x',
-    version='3.4.20',
+    version='3.4.21',
     license='MIT',
     description='GEOPHIRES is a free and open-source geothermal techno-economic simulator.',
     long_description='{}\n{}'.format(
diff --git a/src/geophires_x/__init__.py b/src/geophires_x/__init__.py
index 9428e3c5..62add68f 100644
--- a/src/geophires_x/__init__.py
+++ b/src/geophires_x/__init__.py
@@ -1 +1 @@
-__version__ = '3.4.20'
+__version__ = '3.4.21'