diff --git a/enumset.cabal b/enumset.cabal
--- a/enumset.cabal
+++ b/enumset.cabal
@@ -1,10 +1,9 @@
 Name:             enumset
-Version:          0.0
+Version:          0.0.1
 License:          BSD3
 License-File:     LICENSE
 Author:           Henning Thielemann <haskell@henning-thielemann.de>
 Maintainer:       Henning Thielemann <haskell@henning-thielemann.de>
-Homepage:         http://code.haskell.org/~thielema/enumset/
 Category:         Data, Foreign
 Synopsis:         Sets of enumeration values represented by machine words
 Description:
@@ -20,14 +19,23 @@
   however our implementation allows you to choose the embedding type
   and thus the maximum size of the set.
 -- Portability:      Haskell98
-Cabal-Version:    >=1.2
+Cabal-Version:    >=1.6
 Tested-With:      GHC==6.10.4, GHC==6.12.3
 Build-Type:       Simple
 
+Source-Repository this
+  Tag:         0.0.1
+  Type:        darcs
+  Location:    http://code.haskell.org/~thielema/enumset/
+
+Source-Repository head
+  Type:        darcs
+  Location:    http://code.haskell.org/~thielema/enumset/
+
 Library
   Build-Depends:
     storable-record >=0.0.1 && <0.1,
-    base >= 4 && <6
+    base >= 4 && <5
 
   GHC-Options:      -Wall
   Hs-Source-Dirs:   src
diff --git a/src/Data/EnumSet.hs b/src/Data/EnumSet.hs
--- a/src/Data/EnumSet.hs
+++ b/src/Data/EnumSet.hs
@@ -9,6 +9,7 @@
    fromEnums,
    toEnums,
    intToEnums,
+   null,
    empty,
    (.&.),
    (.|.),
@@ -29,7 +30,7 @@
 import Foreign.Storable (Storable(..), )
 
 import qualified Prelude as P
-import Prelude hiding (fromEnum, toEnum, flip, )
+import Prelude hiding (fromEnum, toEnum, null, flip, )
 
 
 newtype T word enum = Cons {decons :: word}
@@ -60,6 +61,9 @@
    zip [P.toEnum 0 ..] . iterate (P.flip div 2) .
    decons
 
+
+null :: (Enum a, Bits w) => T w a -> Bool
+null (Cons x)  =  x==0
 
 empty :: (Enum a, Bits w) => T w a
 empty = Cons 0