diff --git a/converter.py b/converter.py
index 88d52c0e1e566446d9d0e68debd6152b33de0f45..0d55a79d7de3c8c63e9b24b6e75ef030dc8f6cb3 100644
--- a/converter.py
+++ b/converter.py
@@ -70,6 +70,10 @@ class TestConverter(unittest.TestCase):
         res = self.c.convert(10)
         self.assertEqual(res, 'X')
 
+    def test_convertTwo(self):
+        res = self.c.convert(21)
+        self.assertEqual(res, 'XXI')
+