diff --git a/tests/test_main.py b/tests/test_main.py
index dfff719ac..1029dcadb 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -14,6 +14,11 @@ from aider.main import main
 class TestMain(TestCase):
     def setUp(self):
         os.environ["OPENAI_API_KEY"] = "deadbeef"
+
+        # Force this so that GitHub Actions windows tests don't barf on rich.Console().rule()
+        # https://github.com/Textualize/rich/issues/2411
+        os.environ["PYTHONIOENCODING"] = "utf-8"
+
         self.original_cwd = os.getcwd()
         self.tempdir = tempfile.mkdtemp()
         os.chdir(self.tempdir)