diff --git a/grenade.cabal b/grenade.cabal
index ae84102..784c5ff 100644
--- a/grenade.cabal
+++ b/grenade.cabal
@@ -57,6 +57,7 @@ library
 
   if impl(ghc < 8.0)
     ghc-options:       -fno-warn-incomplete-patterns
+    cpp-options:       -DType=*
 
   if impl(ghc >= 8.6)
     default-extensions: NoStarIsType
diff --git a/src/Grenade/Core/Layer.hs b/src/Grenade/Core/Layer.hs
index 7a9f2f2..db62808 100644
--- a/src/Grenade/Core/Layer.hs
+++ b/src/Grenade/Core/Layer.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE GADTs                 #-}
 {-# LANGUAGE TypeOperators         #-}
@@ -41,7 +42,9 @@ import           Control.Monad.Random ( MonadRandom )
 
 import           Data.List ( foldl' )
 
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core.Shape
 import           Grenade.Core.LearningParameters
diff --git a/src/Grenade/Core/Network.hs b/src/Grenade/Core/Network.hs
index ec1a2a2..f7b1f00 100644
--- a/src/Grenade/Core/Network.hs
+++ b/src/Grenade/Core/Network.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE BangPatterns          #-}
 {-# LANGUAGE GADTs                 #-}
@@ -36,7 +37,9 @@ import           Data.Singletons
 import           Data.Singletons.Prelude
 import           Data.Serialize
 
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core.Layer
 import           Grenade.Core.LearningParameters
diff --git a/src/Grenade/Layers/Concat.hs b/src/Grenade/Layers/Concat.hs
index 1ea18ec..ca3eba6 100644
--- a/src/Grenade/Layers/Concat.hs
+++ b/src/Grenade/Layers/Concat.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE GADTs                 #-}
 {-# LANGUAGE TypeOperators         #-}
@@ -26,7 +27,10 @@ import           Data.Serialize
 
 import           Data.Singletons
 import           GHC.TypeLits
+
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core
 
diff --git a/src/Grenade/Layers/Convolution.hs b/src/Grenade/Layers/Convolution.hs
index 13ca165..11dc9c1 100644
--- a/src/Grenade/Layers/Convolution.hs
+++ b/src/Grenade/Layers/Convolution.hs
@@ -36,7 +36,9 @@ import           GHC.TypeLits hiding (natVal)
 #else
 import           GHC.TypeLits
 #endif
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Numeric.LinearAlgebra hiding ( uniformSample, konst )
 import qualified Numeric.LinearAlgebra as LA
diff --git a/src/Grenade/Layers/Crop.hs b/src/Grenade/Layers/Crop.hs
index a0cf181..0634bca 100644
--- a/src/Grenade/Layers/Crop.hs
+++ b/src/Grenade/Layers/Crop.hs
@@ -28,7 +28,9 @@ import           GHC.TypeLits hiding (natVal)
 #else
 import           GHC.TypeLits
 #endif
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core
 import           Grenade.Layers.Internal.Pad
diff --git a/src/Grenade/Layers/Deconvolution.hs b/src/Grenade/Layers/Deconvolution.hs
index 0f4597a..8e3926b 100644
--- a/src/Grenade/Layers/Deconvolution.hs
+++ b/src/Grenade/Layers/Deconvolution.hs
@@ -40,7 +40,9 @@ import           GHC.TypeLits hiding (natVal)
 #else
 import           GHC.TypeLits
 #endif
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Numeric.LinearAlgebra hiding ( uniformSample, konst )
 import qualified Numeric.LinearAlgebra as LA
diff --git a/src/Grenade/Layers/Merge.hs b/src/Grenade/Layers/Merge.hs
index 8a9c814..f5333f2 100644
--- a/src/Grenade/Layers/Merge.hs
+++ b/src/Grenade/Layers/Merge.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE GADTs                 #-}
 {-# LANGUAGE TypeOperators         #-}
@@ -23,7 +24,9 @@ import           Data.Serialize
 
 import           Data.Singletons
 
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core
 
diff --git a/src/Grenade/Layers/Pad.hs b/src/Grenade/Layers/Pad.hs
index 788153a..652a778 100644
--- a/src/Grenade/Layers/Pad.hs
+++ b/src/Grenade/Layers/Pad.hs
@@ -28,7 +28,9 @@ import           GHC.TypeLits hiding (natVal)
 #else
 import           GHC.TypeLits
 #endif
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core
 import           Grenade.Layers.Internal.Pad
diff --git a/src/Grenade/Layers/Pooling.hs b/src/Grenade/Layers/Pooling.hs
index ea8e001..ecfb9ee 100644
--- a/src/Grenade/Layers/Pooling.hs
+++ b/src/Grenade/Layers/Pooling.hs
@@ -29,7 +29,9 @@ import           GHC.TypeLits hiding (natVal)
 #else
 import           GHC.TypeLits
 #endif
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core
 import           Grenade.Layers.Internal.Pooling
diff --git a/src/Grenade/Recurrent/Core/Layer.hs b/src/Grenade/Recurrent/Core/Layer.hs
index 2611cbc..9124371 100644
--- a/src/Grenade/Recurrent/Core/Layer.hs
+++ b/src/Grenade/Recurrent/Core/Layer.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE TypeFamilies          #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
@@ -8,7 +9,9 @@ module Grenade.Recurrent.Core.Layer (
   , RecurrentUpdateLayer (..)
   ) where
 
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core
 
diff --git a/src/Grenade/Recurrent/Core/Network.hs b/src/Grenade/Recurrent/Core/Network.hs
index 8ad0c1b..62df741 100644
--- a/src/Grenade/Recurrent/Core/Network.hs
+++ b/src/Grenade/Recurrent/Core/Network.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE GADTs                 #-}
 {-# LANGUAGE TypeOperators         #-}
@@ -32,7 +33,9 @@ import           Data.Singletons ( SingI )
 import           Data.Singletons.Prelude ( Head, Last )
 import           Data.Serialize
 
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core
 import           Grenade.Recurrent.Core.Layer
diff --git a/src/Grenade/Recurrent/Layers/BasicRecurrent.hs b/src/Grenade/Recurrent/Layers/BasicRecurrent.hs
index 3be165e..5dfa8e7 100644
--- a/src/Grenade/Recurrent/Layers/BasicRecurrent.hs
+++ b/src/Grenade/Recurrent/Layers/BasicRecurrent.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE GADTs                 #-}
 {-# LANGUAGE RecordWildCards       #-}
@@ -18,7 +19,9 @@ import           Control.Monad.Random ( MonadRandom, getRandom )
 
 import           Data.Singletons.TypeLits
 
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Numeric.LinearAlgebra.Static
 
diff --git a/src/Grenade/Recurrent/Layers/ConcatRecurrent.hs b/src/Grenade/Recurrent/Layers/ConcatRecurrent.hs
index 71e34d4..65aa197 100644
--- a/src/Grenade/Recurrent/Layers/ConcatRecurrent.hs
+++ b/src/Grenade/Recurrent/Layers/ConcatRecurrent.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE GADTs                 #-}
 {-# LANGUAGE TypeOperators         #-}
@@ -27,7 +28,9 @@ import           Data.Serialize
 import           Data.Singletons
 import           GHC.TypeLits
 
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import           Grenade.Core
 import           Grenade.Recurrent.Core
diff --git a/src/Grenade/Recurrent/Layers/LSTM.hs b/src/Grenade/Recurrent/Layers/LSTM.hs
index 5f9b4bc..f0ac79a 100644
--- a/src/Grenade/Recurrent/Layers/LSTM.hs
+++ b/src/Grenade/Recurrent/Layers/LSTM.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE CPP                   #-}
 {-# LANGUAGE BangPatterns          #-}
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE GADTs                 #-}
@@ -23,7 +24,9 @@ import           Data.Proxy
 import           Data.Serialize
 import           Data.Singletons.TypeLits
 
+#if MIN_VERSION_base(4,9,0)
 import           Data.Kind (Type)
+#endif
 
 import qualified Numeric.LinearAlgebra as LA
 import           Numeric.LinearAlgebra.Static