diff --git a/num2words/lang_KO.py b/num2words/lang_KO.py
index 65f4531e..b59aceda 100644
--- a/num2words/lang_KO.py
+++ b/num2words/lang_KO.py
@@ -95,6 +95,8 @@ def to_ordinal(self, value):
         self.verify_ordinal(value)
         if value == 1:
             return "첫 번째"
+        if value == 100:
+            return "백 번째"
         outwords = self.to_cardinal(value).split(" ")
         lastwords = outwords[-1].split("백")
         if "십" in lastwords[-1]:
@@ -107,7 +109,8 @@ def to_ordinal(self, value):
                 pass
             lastwords[-1] = ''.join(ten_one)
         else:
-            lastwords[-1] = self.ords[lastwords[-1]]
+            if lastwords[-1] in self.ords:
+                lastwords[-1] = self.ords[lastwords[-1]]
         outwords[-1] = "백 ".join(lastwords)
         return " ".join(outwords) + " 번째"
 
diff --git a/tests/test_ko.py b/tests/test_ko.py
index c98ad881..085d0c09 100644
--- a/tests/test_ko.py
+++ b/tests/test_ko.py
@@ -83,7 +83,8 @@ def test_currency(self):
 
     def test_ordinal(self):
         cases = [(1, "첫 번째"), (101, "백 한 번째"), (2, "두 번째"), (5, "다섯 번째"),
-                 (10, "열 번째"), (25, "스물다섯 번째"), (137, "백 서른일곱 번째")]
+                 (10, "열 번째"), (100, "백 번째"), (1000, "천 번째"), (10000, "만 번째"),
+                 (25, "스물다섯 번째"), (137, "백 서른일곱 번째")]
         for num, out in cases:
             self.assertEqual(n2k(num, to="ordinal"), out)