diff --git a/converter.py b/converter.py
index 0c6ef0978e8317fc1344d086393a4dd6a2badc2f..50e6a1bd634376d17e3c567a3333a24ae4388913 100644
--- a/converter.py
+++ b/converter.py
@@ -26,7 +26,7 @@ class IConverter(ABC):
 
 class Converter(IConverter):
     def convert(self, num: int) -> str:
-        roman_numbers = [(1000, 'M'), (500, 'D'), (100, 'C'), (50, 'L'), (40, 'XL'), (10, 'X'), (9, 'IX'), (5, 'V'), (4, 'IV'), (1, 'I')]
+        roman_numbers = [(1000, 'M'), (500, 'D'), (100, 'C'), (90, 'XC'), (50, 'L'), (40, 'XL'), (10, 'X'), (9, 'IX'), (5, 'V'), (4, 'IV'), (1, 'I')]
         
         roman_str = ''
 
@@ -94,6 +94,10 @@ class TestConverter(unittest.TestCase):
         res = self.c.convert(1111)
         self.assertEqual(res, 'MCXI')
 
+    def test_convertNintyNine(self):
+        res = self.c.convert(99)
+        self.assertEqual(res, 'XCIX')
+