diff --git a/Language/Atom/Expressions.hs b/Language/Atom/Expressions.hs
--- a/Language/Atom/Expressions.hs
+++ b/Language/Atom/Expressions.hs
@@ -99,7 +99,7 @@
   | Word64
   | Float
   | Double
-  deriving (Show, Read, Eq, Ord)
+  deriving (Show, Read, Eq, Ord, Enum)
 
 data Const
   = CBool   Bool
diff --git a/atom.cabal b/atom.cabal
--- a/atom.cabal
+++ b/atom.cabal
@@ -1,5 +1,5 @@
 name:    atom
-version: 1.0.4
+version: 1.0.5
 
 category: Language
 
@@ -33,7 +33,7 @@
 
 library
     build-depends:
-        base       >= 4.2     && < 5,
+        base       >= 4.0     && < 5,
         mtl        >= 1.1.0.1 && < 1.2,
         process    >= 1.0.1.1 && < 1.2