diff --git a/hlint.cabal b/hlint.cabal
--- a/hlint.cabal
+++ b/hlint.cabal
@@ -1,7 +1,7 @@
 cabal-version:      >= 1.6
 build-type:         Simple
 name:               hlint
-version:            1.8.46
+version:            1.8.47
 license:            BSD3
 license-file:       LICENSE
 category:           Development
diff --git a/src/Util.hs b/src/Util.hs
--- a/src/Util.hs
+++ b/src/Util.hs
@@ -70,8 +70,10 @@
 headDef x [] = x
 headDef x (y:ys) = y
 
+#if !MIN_VERSION_base(4,7,0)
 isLeft Left{} = True; isLeft _ = False
 isRight = not . isLeft
+#endif
 
 unzipEither :: [Either a b] -> ([a], [b])
 unzipEither (x:xs) = case x of