diff --git a/src/Data.Range.purs b/src/Data.Range.purs
index 3c02f65..9cc4f55 100644
--- a/src/Data.Range.purs
+++ b/src/Data.Range.purs
@@ -11,6 +11,10 @@ data RangeOrExact a
   = RangeNotExact (Range a)
   | RangeExact a
 
+instance Functor RangeOrExact where
+  map f (RangeExact a) = RangeExact $ f a
+  map f (RangeNotExact r) = RangeNotExact $ map f r
+
 data Bound a
   = BoundIncluding a
   | BoundExcluding a