diff --git a/tests/basic/test_io.py b/tests/basic/test_io.py
index c7e29185d..bbc467db5 100644
--- a/tests/basic/test_io.py
+++ b/tests/basic/test_io.py
@@ -169,6 +169,7 @@ class TestInputOutput(unittest.TestCase):
         commands = MagicMock()
         commands.get_commands.return_value = ["model", "chat", "help"]
         commands.get_completions.return_value = ["gpt-3.5-turbo", "gpt-4"]
+        commands.matching_commands.return_value = (["model"], None, None)
 
         autocompleter = AutoCompleter(root, rel_fnames, addable_rel_fnames, commands, "utf-8")
 
@@ -176,6 +177,7 @@ class TestInputOutput(unittest.TestCase):
         result = autocompleter.get_command_completions("/model gpt", ["/model", "gpt"])
         self.assertEqual(result, ["gpt-3.5-turbo", "gpt-4"])
         commands.get_completions.assert_called_once_with("model")
+        commands.matching_commands.assert_called_once_with("/model")
 
 
 if __name__ == "__main__":