@@ -1259,7 +1259,7 @@ def test_method_with_pointer_array_argument():
 
 def test_method_call_implicit_conversion():
 
-    class Answer:
+    class IntAnswerMixin:
         # For Python >= 3.8
         def __index__(self):
             return 42
@@ -1268,7 +1268,10 @@ def __index__(self):
         def __int__(self):
             return 42
 
-    class FloatAnswer(Answer):
+    class Answer(int, IntAnswerMixin):
+        pass
+
+    class FloatAnswer(float, IntAnswerMixin):
         def __float__(self):
             return 42.0
 
@@ -1281,3 +1284,13 @@ def __float__(self):
             compare_to = min_value.CompareTo.__overloads__[t]
 
             assert compare_to(v) == -1
+
+    class SomeNonFloat:
+        def __float__(self):
+            return 42.0
+
+    for t in [System.Double, System.Single]:
+        with pytest.raises(TypeError):
+            min_value = t(t.MinValue)
+            compare_to = min_value.CompareTo.__overloads__[t]
+            assert compare_to(SomeNonFloat()) == -1