diff --git a/src/Error/Diagnose/Report/Internal.hs b/src/Error/Diagnose/Report/Internal.hs
index 7b9e303..2a2afac 100644
--- a/src/Error/Diagnose/Report/Internal.hs
+++ b/src/Error/Diagnose/Report/Internal.hs
@@ -124,7 +124,7 @@ data Marker msg
     Maybe msg
   | -- | An empty marker, whose sole purpose is to include a line of code in the report without markers under.
     Blank
-  deriving (Functor, Eq, Ord)
+  deriving (Eq, Ord, Functor, Foldable, Traversable)
 
 isBlank :: Marker msg -> Bool
 isBlank = \case