diff --git a/.github/workflows/check-test-release.yml b/.github/workflows/check-test-release.yml
index d2516ab..a066fba 100644
--- a/.github/workflows/check-test-release.yml
+++ b/.github/workflows/check-test-release.yml
@@ -26,7 +26,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python: ["3.10", "3.11", "3.12", "3.13"]
+        python: ["3.9", "3.10", "3.11", "3.12", "3.13"]
 
     steps:
     - uses: actions/checkout@v5
diff --git a/pyproject.toml b/pyproject.toml
index 2a06f67..9c0f4c5 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -12,6 +12,7 @@ keywords = ["git", "repo", "repository", "artifact", "registry", "developer-tool
 classifiers = [
     "Development Status :: 2 - Pre-Alpha",
     "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.9",
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
diff --git a/tests/conftest.py b/tests/conftest.py
index d2c69d3..c6ada54 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -1,4 +1,5 @@
 # pylint: disable=redefined-outer-name
+import inspect
 import os
 import sys
 from time import sleep
@@ -18,7 +19,13 @@
 
 class Runner:
     def __init__(self):
-        self._runner = CliRunner()
+        # Older versions of CliRunner need this
+        # Can we removed when we drop Py 3.9 support
+        init_sig = inspect.signature(CliRunner.__init__)
+        if "mix_stderr" in init_sig.parameters:
+            self._runner = CliRunner(mix_stderr=False)  # pylint: disable=unexpected-keyword-arg
+        else:
+            self._runner = CliRunner()
 
     def invoke(self, *args, **kwargs) -> Result:
         return self._runner.invoke(app, *args, **kwargs)