diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+# Version 0.1
+
+* Changed the type of `middleware` so that the previous *lookup*
+  function is not used anymore. Instead, a `CryptoCookie` is
+  provided directly to an `Application`-construction function.
+
 # Version 0.0.1
 
 * Initial version.
diff --git a/lib/Wai/CryptoCookie.hs b/lib/Wai/CryptoCookie.hs
--- a/lib/Wai/CryptoCookie.hs
+++ b/lib/Wai/CryptoCookie.hs
@@ -7,22 +7,8 @@
 -- import qualified "Wai.CryptoCookie"
 -- @
 --
--- One example of how to obtain a new "Network.Wai".'Network.Wai.Middleware',
---
--- @
--- do (__middleware__, __lookup__) <- do
---       key <- "Wai.CryptoCookie".'autoKeyFileBase16' \"\/run\/my-cookie-encryption-key\"
---       "Wai.CryptoCookie".'middleware' ("Wai.CryptoCookie".'defaultConfig' key)
--- @
---
--- The obtained @__middleware__@ shall be applied to your
--- "Network.Wai".'Wai.Application'.
---
--- The obtained @__lookup__@ function can be used to obtain the 'CryptoCookie'
--- associated with each 'Wai.Request'. It returns 'Nothing' if this particular
--- @__middleware__@ was not used on the given 'Wai.Request'.
---
--- Finally, interact with the 'CryptoCookie' data using 'get' or 'set'.
+-- Use 'middleware' to obtain a function to allow an 'Wai.Application' to
+-- interact with a 'CryptoCookie'  using 'get' or 'set'.
 --
 -- == Do I store session data on the client or on the server?
 --
diff --git a/lib/Wai/CryptoCookie/Encryption.hs b/lib/Wai/CryptoCookie/Encryption.hs
--- a/lib/Wai/CryptoCookie/Encryption.hs
+++ b/lib/Wai/CryptoCookie/Encryption.hs
@@ -58,9 +58,10 @@
 
    -- | Generate initial 'Encrypt'ion and 'Decrypt'ion context for a 'Key'.
    --
-   -- The 'Encrypt'ion context could carry for example the next nonce to use
-   -- for 'encrypt'ion, the 'Key' itself or its derivative used during the
-   -- actual 'encrypt'ion process, or a deterministic random number generator.
+   -- The 'Encrypt'ion context could carry for example the next
+   -- __randomly generated nonce__ to use for 'encrypt'ion, the 'Key'
+   -- itself or its derivative used during the actual 'encrypt'ion
+   -- process, or a deterministic random number generator.
    --
    -- The 'Decrypt'ion context could carry for example the 'Key' itself or its
    -- derivative used during the 'decrypt'ion process.
diff --git a/lib/Wai/CryptoCookie/Middleware.hs b/lib/Wai/CryptoCookie/Middleware.hs
--- a/lib/Wai/CryptoCookie/Middleware.hs
+++ b/lib/Wai/CryptoCookie/Middleware.hs
@@ -18,7 +18,6 @@
 import Data.Kind (Type)
 import Data.List (find)
 import Data.Time.Clock.POSIX qualified as Time
-import Data.Vault.Lazy qualified as V
 import Network.Wai qualified as Wai
 import Web.Cookie
    ( SetCookie (..)
@@ -91,31 +90,36 @@
 set :: CryptoCookie a -> Maybe a -> STM ()
 set (CryptoCookie _ x) = writeTVar x . Just
 
--- | Construct a new 'Middleware', and function that can be used to look-up the
--- 'CryptoCookie' on each incoming 'Wai.Request'. Said function returns
--- 'Nothing' if the 'Middleware' was not used on the 'Wai.Request'.
+-- | Obtain a new 'Wai.Application'-transforming function (more or less a
+-- 'Wai.Middleware') wherein the 'Wai.Application' being transformed can interact
+-- with a 'CryptoCookie'.
+--
+-- * 'middleware' can be called multiple times as long as the 'setCookieName'
+-- for the 'SetCookie' specified in 'Config' is different each time.
+--
+-- * It is safe to reuse the same 'Key' for multiple 'middleware' calls.  Each
+-- time the 'Key' will have a different randomly 'initial'ized 'Encrypt'ion
+-- context.
 middleware
    :: forall a m
     . (MonadIO m)
    => Config a
    -- ^ Consider using 'Wai.CryptoCookie.defaultConfig'.
-   -> m (Wai.Middleware, Wai.Request -> Maybe (CryptoCookie a))
+   -> m ((CryptoCookie a -> Wai.Application) -> Wai.Application)
+   -- ^ Remember that 'Wai.Middleware' is a type-synonym for
+   -- @'Wai.Application' -> 'Wai.Application'@.  This type is not too different
+   -- from that.
 middleware c = liftIO do
    env <- newEnv c
-   vk :: V.Key (CryptoCookie a) <- V.newKey
-   pure
-      ( \app req respond -> do
-         tv <- newTVarIO Nothing
-         let ck = CryptoCookie (getRequestCookieData env req) tv
-         app (req{Wai.vault = V.insert vk ck (Wai.vault req)}) \res -> do
-            yya1 <- readTVarIO tv
-            let f = case yya1 of
-                  Nothing -> pure
-                  Just Nothing -> expireResponseCookieData env
-                  Just (Just a1) -> setResponseCookieData env a1
-            respond =<< f res
-      , \req -> V.lookup vk (Wai.vault req)
-      )
+   pure \fapp -> \req respond -> do
+      tv <- newTVarIO Nothing
+      fapp (CryptoCookie (getRequestCookieData env req) tv) req \res -> do
+         yya1 <- readTVarIO tv
+         let f = case yya1 of
+               Nothing -> pure
+               Just Nothing -> expireResponseCookieData env
+               Just (Just a1) -> setResponseCookieData env a1
+         respond =<< f res
 
 -- | Find, decrypt and decode the cookie value from the 'Wai.Request'.
 --
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -74,72 +74,65 @@
    c1 <- do
       c <- fmap WCC.defaultConfig WCC.genKey
       pure c{WCC.key = k}
-   (mw1, look1) <- WCC.middleware c1
+   fmw1 <- WCC.middleware c1
 
-   WT.withSession (app look1 id) do
+   WT.withSession (fmw1 $ app id) do
       sres1 <- WT.request WT.defaultRequest
       WT.assertBody "Nothing" sres1
       WT.assertNoClientCookieExists "t1-a" "SESSION"
 
-   WT.withSession (mw1 $ app look1 id) do
       sres1 <- WT.request WT.defaultRequest
-      WT.assertBody "Just Nothing" sres1
-      WT.assertNoClientCookieExists "t2-a" "SESSION"
-
-      sres1 <- WT.request WT.defaultRequest
-      WT.assertBody "Just Nothing" sres1
-      WT.assertNoClientCookieExists "t2-b" "SESSION"
+      WT.assertBody "Nothing" sres1
+      WT.assertNoClientCookieExists "t1-b" "SESSION"
 
-   ck0 <- WT.withSession (mw1 $ app look1 (\_ -> Just 900)) do
+   ck0 <- WT.withSession (fmw1 $ app \_ -> Just 900) do
       sres1 <- WT.request WT.defaultRequest
-      WT.assertBody "Just Nothing" sres1
-      WT.assertClientCookieExists "t3-a" "SESSION"
+      WT.assertBody "Nothing" sres1
+      WT.assertClientCookieExists "t2-a" "SESSION"
 
       sres2 <- WT.request WT.defaultRequest
-      WT.assertBody "Just (Just 900)" sres2
-      WT.assertClientCookieExists "t3-b" "SESSION"
+      WT.assertBody "Just 900" sres2
+      WT.assertClientCookieExists "t2-b" "SESSION"
 
       WT.getClientCookies
 
-   WT.withSession (mw1 $ app look1 (\_ -> Nothing)) do
+   WT.withSession (fmw1 $ app \_ -> Nothing) do
       WT.modifyClientCookies \_ -> ck0
 
       sres1 <- WT.request WT.defaultRequest
-      WT.assertBody "Just (Just 900)" sres1
-      WT.assertClientCookieExists "t4-a" "SESSION"
+      WT.assertBody "Just 900" sres1
+      WT.assertClientCookieExists "t3-a" "SESSION"
 
       sres2 <- WT.request WT.defaultRequest
-      WT.assertBody "Just Nothing" sres2
-      WT.assertClientCookieExists "t4-b" "SESSION"
-      WT.assertClientCookieValue "t4-c" "SESSION" ""
+      WT.assertBody "Nothing" sres2
+      WT.assertClientCookieExists "t3-b" "SESSION"
+      WT.assertClientCookieValue "t3-c" "SESSION" ""
 
-   WT.withSession (mw1 $ app look1 (fmap (+ 1))) do
+   WT.withSession (fmw1 $ app (fmap (+ 1))) do
       sres1 <- WT.request WT.defaultRequest
-      WT.assertBody "Just Nothing" sres1
-      WT.assertNoClientCookieExists "t5-a" "SESSION"
+      WT.assertBody "Nothing" sres1
+      WT.assertNoClientCookieExists "t4-a" "SESSION"
 
       WT.modifyClientCookies \_ -> ck0
 
       sres2 <- WT.request WT.defaultRequest
-      WT.assertBody "Just (Just 900)" sres2
-      WT.assertClientCookieExists "t5-b" "SESSION"
+      WT.assertBody "Just 900" sres2
+      WT.assertClientCookieExists "t4-b" "SESSION"
 
       sres2 <- WT.request WT.defaultRequest
-      WT.assertBody "Just (Just 901)" sres2
-      WT.assertClientCookieExists "t5-c" "SESSION"
+      WT.assertBody "Just 901" sres2
+      WT.assertClientCookieExists "t4-c" "SESSION"
 
 app
-   :: (W.Request -> Maybe (WCC.CryptoCookie Word))
-   -> (Maybe Word -> Maybe Word)
+   :: (Maybe Word -> Maybe Word)
+   -> WCC.CryptoCookie Word
    -> W.Application
-app look g = \req res -> do
-   yyold <- forM (look req) \cc -> do
-      let yold = WCC.get cc
-          ynew = g yold
-      when (ynew /= yold) do
-         atomically $ WCC.set cc ynew
-      pure yold
-   res $ W.responseLBS HT.status200 [] $ fromString $ show yyold
+app g cc = \req res -> do
+   let yold = WCC.get cc
+       ynew = g yold
+   when (ynew /= yold) do
+      atomically $ WCC.set cc ynew
+   res $ W.responseLBS HT.status200 [] $ fromString $ show yold
 
 withTmpDir :: (FilePath -> IO a) -> IO a
 withTmpDir f = do
diff --git a/wai-cryptocookie.cabal b/wai-cryptocookie.cabal
--- a/wai-cryptocookie.cabal
+++ b/wai-cryptocookie.cabal
@@ -1,6 +1,6 @@
 cabal-version: 2.4
 name: wai-cryptocookie
-version: 0.0.1
+version: 0.1
 license: Apache-2.0
 license-file: LICENSE
 extra-source-files: README.md CHANGELOG.md
@@ -53,7 +53,6 @@
     stm,
     text,
     time,
-    vault,
     wai,
 
 test-suite test