diff --git a/Control/Categorical/Functor.hs b/Control/Categorical/Functor.hs
--- a/Control/Categorical/Functor.hs
+++ b/Control/Categorical/Functor.hs
@@ -21,7 +21,7 @@
 import Control.Category
 import Prelude hiding (id, (.), Functor(..))
 import qualified Prelude
-#ifdef GLASGOW_HASKELL
+#ifdef __GLASGOW_HASKELL__
 import Data.Data (Data(..), mkDataType, DataType, mkConstr, Constr, constrIndex, Fixity(..))
 import Data.Typeable (Typeable1(..), TyCon, mkTyCon, mkTyConApp, gcast1)
 #endif
@@ -30,7 +30,7 @@
 newtype LiftedFunctor f a = LiftedFunctor (f a)
     deriving (Show, Read)
 
-#ifdef GLASGOW_HASKELL
+#ifdef __GLASGOW_HASKELL__
 
 liftedTyCon :: TyCon
 liftedTyCon = mkTyCon "Control.Categorical.Functor.LiftedFunctor"
@@ -62,7 +62,7 @@
 newtype LoweredFunctor f a = LoweredFunctor (f a)
     deriving (Show, Read)
 
-#ifdef GLASGOW_HASKELL
+#ifdef __GLASGOW_HASKELL__
 
 loweredTyCon :: TyCon
 loweredTyCon = mkTyCon "Control.Categorical.Functor.LoweredFunctor"
diff --git a/Control/Category/Dual.hs b/Control/Category/Dual.hs
--- a/Control/Category/Dual.hs
+++ b/Control/Category/Dual.hs
@@ -14,10 +14,10 @@
 	( Dual(..)
 	) where
 
-import Prelude ()
+import Prelude (undefined,const,error)
 import Control.Category
 
-#ifdef GLASGOW_HASKELL
+#ifdef __GLASGOW_HASKELL__
 import Data.Data (Data(..), mkDataType, DataType, mkConstr, Constr, constrIndex, Fixity(..))
 import Data.Typeable (Typeable2(..), TyCon, mkTyCon, mkTyConApp, gcast1)
 #endif
@@ -28,7 +28,7 @@
 	id = Dual id
 	Dual f . Dual g = Dual (g . f)
 
-#ifdef GLASGOW_HASKELL
+#ifdef __GLASGOW_HASKELL__
 instance Typeable2 (~>) => Typeable2 (Dual (~>)) where
     typeOf2 tfab = mkTyConApp dataTyCon [typeOf2 (undefined `asDualArgsType` tfab)]
         where asDualArgsType :: f b a -> t f a b -> f b a
diff --git a/categories.cabal b/categories.cabal
--- a/categories.cabal
+++ b/categories.cabal
@@ -1,6 +1,6 @@
 name:          categories
 category:      Control
-version:       0.58.0.3
+version:       0.58.0.4
 license:       BSD3
 cabal-version: >= 1.2.3
 license-file:  LICENSE