1 files changed, 6 insertions, 2 deletions
diff --git a/testsuite/tests/simplCore/should_run/T13429a.hs b/testsuite/tests/simplCore/should_run/T13429a.hs
index 6a838cb79c..1c394888d6 100644
--- a/testsuite/tests/simplCore/should_run/T13429a.hs
+++ b/testsuite/tests/simplCore/should_run/T13429a.hs
@@ -3,7 +3,9 @@
 {-# LANGUAGE FunctionalDependencies #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE UndecidableInstances #-}
-module T13429a where -- Orignally FingerTree.hs from the ticket
+module T13429a where -- Originally FingerTree.hs from the ticket
+
+import Data.Semigroup (Semigroup(..))
 
 class (Monoid v) => Measured v a | a -> v where
     measure :: a -> v
@@ -32,9 +34,11 @@ instance Foldable (FingerTree v) where
     foldMap f (Deep _ pr m sf) =
         foldMap f pr `mappend` foldMap (foldMap f) m `mappend` foldMap f sf
 
+instance Measured v a => Semigroup (FingerTree v a) where
+    (<>) = (><)
+
 instance Measured v a => Monoid (FingerTree v a) where
     mempty = empty
-    mappend = (><)
 
 empty :: Measured v a => FingerTree v a
 empty = Empty