diff --git a/lib/koans/03_numbers.ex b/lib/koans/03_numbers.ex
index 4bed3b9..fdfdcb5 100644
--- a/lib/koans/03_numbers.ex
+++ b/lib/koans/03_numbers.ex
@@ -123,8 +123,11 @@ defmodule Numbers do
     assert 0 in range == ___
   end
 
+  def is_range?(%Range{}), do: true
+  def is_range?(_), do: false
+
   koan "Is this a range?" do
-    assert Range.range?(1..10) == ___
-    assert Range.range?(0) == ___
+    assert is_range?(1..10) == ___
+    assert is_range?(0) == ___
   end
 end