diff --git a/functor-classes-compat.cabal b/functor-classes-compat.cabal
--- a/functor-classes-compat.cabal
+++ b/functor-classes-compat.cabal
@@ -1,5 +1,5 @@
 name:               functor-classes-compat
-version:            2
+version:            2.0.0.1
 synopsis:           Data.Functor.Classes instances for core packages
 description:
   "Data.Functor.Classes" instances for core packages:
diff --git a/src-implicit/containers/Data/Tree/Functor/Classes.hs b/src-implicit/containers/Data/Tree/Functor/Classes.hs
--- a/src-implicit/containers/Data/Tree/Functor/Classes.hs
+++ b/src-implicit/containers/Data/Tree/Functor/Classes.hs
@@ -2,18 +2,20 @@
 module Data.Tree.Functor.Classes () where
 
 import Data.Functor.Classes
-import Data.Tree            (Tree(..))
+import Data.Tree            (Tree (..))
 
+import qualified Data.Monoid as M
+
 instance Eq1 Tree where eq1 = (==)
 instance Ord1 Tree where
   compare1 (Node a fa) (Node b fb) =
-    compare a b `mappend` liftCompareList compare1 fa fb
+    compare a b `M.mappend` liftCompareList compare1 fa fb
 
 liftCompareList :: (a -> a -> Ordering) -> [a] -> [a] -> Ordering
 liftCompareList cmp = go
   where go [] [] = EQ
         go [] (_:_) = LT
         go (_:_) [] = GT
-        go (a:as) (b:bs) = cmp a b `mappend` go as bs
+        go (a:as) (b:bs) = cmp a b `M.mappend` go as bs
 
 instance Show1 Tree where showsPrec1 = showsPrec