1 files changed, 5 insertions, 0 deletions

diff --git a/src/Crypto/Tox.hs b/src/Crypto/Tox.hs
index effa8520..0df06054 100644
--- a/src/Crypto/Tox.hs
+++ b/src/Crypto/Tox.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE KindSignatures #-}
@@ -59,7 +60,11 @@ import qualified Data.ByteString.Base16 as Base16
 import qualified Data.ByteString.Char8  as C8
 import Data.Data
 import Data.Functor.Contravariant
+#if MIN_VERSION_base(4,9,1)
 import Data.Kind
+#else
+import GHC.Exts (Constraint)
+#endif
 import Data.Ord
 import Data.Serialize as S
 import Data.Word