diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,11 @@
+# Version 0.2
+
+* The type of `middleware` is now `Df1 -> Middleware`.
+
+* Introduced a new function `middleware'` to replace the previous
+  *lookup* functionality.
+
+
 # Version 0.1
 
 * Initial version.
diff --git a/di-wai.cabal b/di-wai.cabal
--- a/di-wai.cabal
+++ b/di-wai.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.18
 name: di-wai
-version: 0.1
+version: 0.2
 author: Renzo Carbonara
 maintainer: renλren.zone
 copyright: Renzo Carbonara 2024
@@ -23,7 +23,6 @@
     clock,
     df1-wai,
     di-df1,
-    vault,
     wai
   ghc-options: -Wall -O2
 
diff --git a/lib/Di/Wai.hs b/lib/Di/Wai.hs
--- a/lib/Di/Wai.hs
+++ b/lib/Di/Wai.hs
@@ -6,56 +6,51 @@
 -- @
 -- import qualified "Di.Wai"
 -- @
-module Di.Wai (middleware) where
+module Di.Wai (middleware, middleware') where
 
-import Control.Monad.IO.Class
 import Data.Foldable
 import Data.IORef
-import Data.Vault.Lazy qualified as V
 import Data.Word
 import Df1.Wai qualified
-import Di.Df1 qualified
+import Di.Df1 qualified as Di
 import Network.Wai qualified as Wai
 import System.Clock qualified as Clock
+import System.IO.Unsafe
 
+refReqId :: IORef Word64
+refReqId = unsafePerformIO $ newIORef 0
+{-# NOINLINE refReqId #-}
+
+-- | Like 'middleware', but it exposes the 'Di.Df1' that includes 'Df1.Path'
+-- data about 'Wai.Request' to the underlying 'Wai.Application'.
+middleware'
+   :: Di.Df1
+   -> (Di.Df1 -> Wai.Application)
+   -> Wai.Application
+middleware' di0 = \fapp req respond -> do
+   t0 <- Clock.getTime Clock.Monotonic
+   reqId <- atomicModifyIORef' refReqId $ \ol -> (ol + 1, ol)
+   let di1 =
+         foldl'
+            (\di (k, v) -> Di.attr k v di)
+            (Di.push "http" di0)
+            (("request", Di.value reqId) : Df1.Wai.request req)
+   Di.info_ di1 "Request coming in"
+   fapp di1 req $ \res -> do
+      t1 <- Clock.getTime Clock.Monotonic
+      let td = Clock.toNanoSecs t1 - Clock.toNanoSecs t0
+          di2 =
+            foldl'
+               (\di (k, v) -> Di.attr k v di)
+               di1
+               (("nanoseconds", Di.value td) : Df1.Wai.response res)
+      Di.info_ di2 "Response going out"
+      respond res
+
 -- | Obtain a 'Wai.Middleware' that will log incomming 'Wai.Request's
--- and outgoing 'Wai.Response's.
---
--- @
--- do (__middleware__, __lookup__) <- "Di.Wai".'middleware' di
--- @
---
--- * The obtained @__middleware__@ shall be applied to your 'Wai.Application'.
+-- and outgoing 'Wai.Response's through the given 'Di.Df1'.
 --
--- * The obtained @__lookup__@ function can be used to obtain the 'Di.Df1.Df1'
--- that includes 'Df1.Path' data about 'Wai.Request'. It returns 'Nothing' if
--- this particular @__middleware__@ was not used on the given 'Wai.Request'.
-middleware
-   :: (MonadIO m)
-   => Di.Df1.Df1
-   -> m (Wai.Middleware, Wai.Request -> Maybe Di.Df1.Df1)
-middleware di0 = liftIO $ do
-   ref :: IORef Word64 <- newIORef 0
-   vk :: V.Key Di.Df1.Df1 <- V.newKey
-   pure
-      ( \app req respond -> do
-         t0 <- Clock.getTime Clock.Monotonic
-         reqId <- atomicModifyIORef' ref $ \ol -> (ol + 1, ol)
-         let di1 =
-               foldl'
-                  (\di (k, v) -> Di.Df1.attr k v di)
-                  (Di.Df1.push "http" di0)
-                  (("request", Di.Df1.value reqId) : Df1.Wai.request req)
-         Di.Df1.info_ di1 "Request coming in"
-         app (req{Wai.vault = V.insert vk di1 (Wai.vault req)}) $ \res -> do
-            t1 <- Clock.getTime Clock.Monotonic
-            let td = Clock.toNanoSecs t1 - Clock.toNanoSecs t0
-                di2 =
-                  foldl'
-                     (\di (k, v) -> Di.Df1.attr k v di)
-                     di1
-                     (("nanoseconds", Di.Df1.value td) : Df1.Wai.response res)
-            Di.Df1.info_ di2 "Response going out"
-            respond res
-      , \req -> V.lookup vk (Wai.vault req)
-      )
+-- If your 'Wai.Application' needs access to the 'Di.Df1' uniquely tied
+-- to the current 'Wai.Request', then use 'middleware'' instead.
+middleware :: Di.Df1 -> Wai.Middleware
+middleware di = middleware' di . const