diff --git a/src/Data/Vault/IO.hs b/src/Data/Vault/IO.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Vault/IO.hs
@@ -0,0 +1,70 @@
+module Data.Vault.LAZINESS (
+    -- * Vault
+    Vault, Key,
+    empty, newKey, lookup, insert, adjust, delete, union,
+
+    -- * Locker
+    Locker,
+    lock, unlock,
+    ) where
+
+import Prelude hiding (lookup)
+import Control.Monad.ST
+import qualified Data.Vault.ST.LAZINESS as ST
+
+
+{-----------------------------------------------------------------------------
+    Vault
+------------------------------------------------------------------------------}
+
+-- | A persistent store for values of arbitrary types.
+--
+-- This variant is the simplest and creates keys in the 'IO' monad.
+-- See the module "Data.Vault.ST" if you want to use it with the 'ST' monad instead.
+type Vault = ST.Vault RealWorld
+
+-- | Keys for the vault.
+type Key = ST.Key RealWorld
+
+-- | The empty vault.
+empty :: Vault
+empty = ST.empty
+
+-- | Create a new key for use with a vault.
+newKey :: IO (Key a)
+newKey = stToIO ST.newKey
+
+-- | Lookup the value of a key in the vault.
+lookup :: Key a -> Vault -> Maybe a
+lookup = ST.lookup
+
+-- | Insert a value for a given key. Overwrites any previous value.
+insert :: Key a -> a -> Vault -> Vault
+insert = ST.insert
+
+-- | Adjust the value for a given key if it's present in the vault.
+adjust :: (a -> a) -> Key a -> Vault -> Vault
+adjust = ST.adjust
+
+-- | Delete a key from the vault.
+delete :: Key a -> Vault -> Vault
+delete = ST.delete
+
+-- | Merge two vaults (left-biased).
+union :: Vault -> Vault -> Vault
+union = ST.union
+
+{-----------------------------------------------------------------------------
+    Locker
+------------------------------------------------------------------------------}
+
+-- | A persistent store for a single value.
+type Locker = ST.Locker RealWorld
+
+-- | Put a single value into a 'Locker'.
+lock :: Key a -> a -> Locker
+lock = ST.lock
+
+-- | Retrieve the value from the 'Locker'.
+unlock :: Key a -> Locker -> Maybe a
+unlock = ST.unlock
diff --git a/src/Data/Vault/ST/ST.hs b/src/Data/Vault/ST/ST.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Vault/ST/ST.hs
@@ -0,0 +1,72 @@
+module Data.Vault.ST.LAZINESS (
+    -- * Vault
+    Vault, Key,
+    empty, newKey, lookup, insert, adjust, delete, union,
+
+    -- * Locker
+    Locker,
+    lock, unlock,
+    ) where
+
+import Data.Monoid (Monoid(..))
+import Prelude hiding (lookup)
+import Control.Applicative hiding (empty)
+import Control.Monad.ST
+import Control.Monad.ST.Unsafe as STUnsafe
+
+import Data.Unique.Really
+
+{-
+    The GHC-specific implementation uses  unsafeCoerce
+    for reasons of efficiency.
+
+    See  http://apfelmus.nfshost.com/blog/2011/09/04-vault.html
+    for the second implementation that doesn't need to
+    bypass the type checker.
+-}
+#if UseGHC
+#include "backends/GHC.hs"
+#else
+#include "backends/IORef.hs"
+#endif
+
+{-----------------------------------------------------------------------------
+    Vault
+------------------------------------------------------------------------------}
+
+instance Monoid (Vault s) where
+    mempty = empty
+    mappend = union
+
+-- | The empty vault.
+empty :: Vault s
+empty = Vault Map.empty
+
+-- | Create a new key for use with a vault.
+newKey :: ST s (Key s a)
+
+-- | Lookup the value of a key in the vault.
+lookup :: Key s a -> Vault s -> Maybe a
+
+-- | Insert a value for a given key. Overwrites any previous value.
+insert :: Key s a -> a -> Vault s -> Vault s
+
+-- | Adjust the value for a given key if it's present in the vault.
+adjust :: (a -> a) -> Key s a -> Vault s -> Vault s
+
+-- | Delete a key from the vault.
+delete :: Key s a -> Vault s -> Vault s
+
+-- | Merge two vaults (left-biased).
+union :: Vault s -> Vault s -> Vault s
+union (Vault m) (Vault m') = Vault $ Map.union m m'
+
+{-----------------------------------------------------------------------------
+    Locker
+------------------------------------------------------------------------------}
+
+-- | Put a single value into a 'Locker'.
+lock :: Key s a -> a -> Locker s
+
+-- | Retrieve the value from the 'Locker'.
+unlock :: Key s a -> Locker s -> Maybe a
diff --git a/src/Data/Vault/ST/backends/GHC.hs b/src/Data/Vault/ST/backends/GHC.hs
new file mode 100644
--- /dev/null
+++ b/src/Data/Vault/ST/backends/GHC.hs
@@ -0,0 +1,41 @@
+-- This implementation is specific to GHC
+-- und uses  unsafeCoerce  for reasons of efficiency.
+import GHC.Exts (Any)
+import Unsafe.Coerce (unsafeCoerce)
+
+import qualified Data.HashMap.LAZINESS as Map
+type Map = Map.HashMap
+
+toAny :: a -> Any
+toAny = unsafeCoerce
+
+fromAny :: Any -> a
+fromAny = unsafeCoerce
+
+{-----------------------------------------------------------------------------
+    Vault
+------------------------------------------------------------------------------}
+newtype Vault s = Vault (Map Unique Any)
+newtype Key s a = Key Unique
+
+newKey = STUnsafe.unsafeIOToST $ Key <$> newUnique
+
+lookup (Key k) (Vault m) = fromAny <$> Map.lookup k m
+
+insert (Key k) x (Vault m) = Vault $ Map.insert k (toAny x) m
+
+adjust f (Key k) (Vault m) = Vault $ Map.adjust f' k m
+    where f' = toAny . f . fromAny
+
+delete (Key k) (Vault m) = Vault $ Map.delete k m
+
+{-----------------------------------------------------------------------------
+    Locker
+------------------------------------------------------------------------------}
+data Locker s = Locker !Unique !Any
+
+lock (Key k) = Locker k . toAny
+
+unlock (Key k) (Locker k' a)
+  | k == k' = Just $ fromAny a
+  | otherwise = Nothing
diff --git a/vault.cabal b/vault.cabal
--- a/vault.cabal
+++ b/vault.cabal
@@ -1,5 +1,5 @@
 Name:               vault
-Version:            0.3.0.1
+Version:            0.3.0.2
 Synopsis:           a persistent store for values of arbitrary types
 Description:
   A /vault/ is a persistent store for values of arbitrary types.
@@ -13,6 +13,8 @@
   .
   Changelog:
   .
+  * 0.3.0.2 - Fix tarball.
+  .
   * 0.3.0.1 - Use CPP to reduce code duplication.
   .
   * 0.3.0.0 - Split modules into Lazy and Strict variants, no default choice.
@@ -29,7 +31,11 @@
 build-type:         Simple
 cabal-version:      >= 1.6
 
-extra-source-files: Readme.md
+extra-source-files:
+    Readme.md
+    src/Data/Vault/IO.hs
+    src/Data/Vault/ST/ST.hs
+    src/Data/Vault/ST/backends/GHC.hs
 
 source-repository head
     type:           git