diff --git a/ate/utils.py b/ate/utils.py
index b72cafaf..50a93ad6 100644
--- a/ate/utils.py
+++ b/ate/utils.py
@@ -210,6 +210,8 @@ def match_expected(value, expected, comparator="eq"):
             assert value in expected
         elif comparator in ["regex"]:
             assert re.match(expected, value)
+        else:
+            raise ParamsError("comparator not supported!")
 
         return True
     except AssertionError:
diff --git a/test/test_utils.py b/test/test_utils.py
index 3a191e08..86aacec3 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -197,4 +197,7 @@ class TestUtils(ApiServerUnittest):
         self.assertTrue(utils.match_expected("3ab", "123abc456", "contained_by"))
 
         self.assertTrue(utils.match_expected("123abc456", "^123.*456$", "regex"))
-        self.assertFalse(utils.match_expected("123abc456", "^12b.*456$", "regex"))
\ No newline at end of file
+        self.assertFalse(utils.match_expected("123abc456", "^12b.*456$", "regex"))
+
+        with self.assertRaises(exception.ParamsError):
+            utils.match_expected(1, 2, "not_supported_comparator")