diff --git a/mig.cabal b/mig.cabal
--- a/mig.cabal
+++ b/mig.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:               mig
-version:            0.2.0.0
+version:            0.2.0.1
 synopsis:           Build lightweight and composable servers
 description:        The Core for the mig server library.
                     With library mig we can build lightweight and composable servers.
@@ -68,6 +68,7 @@
       DerivingStrategies
       StrictData
       AllowAmbiguousTypes
+      DataKinds
   ghc-options: -Wall -Wcompat -Widentities -Wincomplete-record-updates -Wincomplete-uni-patterns -Wmissing-export-lists -Wmissing-home-modules -Wpartial-fields -Wredundant-constraints -Wunused-packages
   build-depends:
       aeson
@@ -114,6 +115,7 @@
       DerivingStrategies
       StrictData
       AllowAmbiguousTypes
+      DataKinds
   ghc-options: -Wall -Wcompat -Widentities -Wincomplete-record-updates -Wincomplete-uni-patterns -Wmissing-export-lists -Wmissing-home-modules -Wpartial-fields -Wredundant-constraints -Wunused-packages -threaded -rtsopts -with-rtsopts=-N
   build-depends:
       aeson
diff --git a/src/Mig/Core/Api/NormalForm/TreeApi.hs b/src/Mig/Core/Api/NormalForm/TreeApi.hs
--- a/src/Mig/Core/Api/NormalForm/TreeApi.hs
+++ b/src/Mig/Core/Api/NormalForm/TreeApi.hs
@@ -20,10 +20,11 @@
 
 type CaptureMap = Map Text Text
 
--- | This form of API encodes path switch points as Map's so
--- it does not retraverse the routes and can find the right
--- branch on switch. In the plain api it tries the routes one by one
--- until it finds the right one.
+{-| This form of API encodes path switch points as Map's so
+it does not retraverse the routes and can find the right
+branch on switch. In the plain api it tries the routes one by one
+until it finds the right one.
+-}
 data TreeApi a
   = WithStaticPath [Text] (TreeApi a)
   | WithCapturePath [Text] (TreeApi a)
diff --git a/src/Mig/Core/Class/Route.hs b/src/Mig/Core/Class/Route.hs
--- a/src/Mig/Core/Class/Route.hs
+++ b/src/Mig/Core/Class/Route.hs
@@ -1,7 +1,8 @@
 {-# LANGUAGE UndecidableInstances #-}
 
--- | Creation of routes from functions. A route is a handler function
--- for single path of the server.
+{-| Creation of routes from functions. A route is a handler function
+for single path of the server.
+-}
 module Mig.Core.Class.Route (
   Route (..),
   ToRoute (..),
diff --git a/src/Mig/Core/Server.hs b/src/Mig/Core/Server.hs
--- a/src/Mig/Core/Server.hs
+++ b/src/Mig/Core/Server.hs
@@ -103,10 +103,11 @@
 mapResponse :: (Functor m) => (Response -> Response) -> Server m -> Server m
 mapResponse f = mapServerFun $ \fun -> fmap (fmap f) . fun
 
--- | API route finder strategy. The API can be transformed to some normal form
--- for faster route lookup. So far we have two normal forms.
--- One is plain Api type as it is. And another one is tree-structure
--- where path switches are encoded with Map's.
+{-| API route finder strategy. The API can be transformed to some normal form
+for faster route lookup. So far we have two normal forms.
+One is plain Api type as it is. And another one is tree-structure
+where path switches are encoded with Map's.
+-}
 data FindRoute normalForm m = FindRoute
   { toNormalForm :: Api (Route m) -> normalForm (Route m)
   , getPath :: [Text] -> normalForm (Route m) -> Maybe (Route m, Api.CaptureMap)
diff --git a/src/Mig/Core/Server/Cache.hs b/src/Mig/Core/Server/Cache.hs
--- a/src/Mig/Core/Server/Cache.hs
+++ b/src/Mig/Core/Server/Cache.hs
@@ -21,32 +21,38 @@
 -- | Cache config
 data CacheConfig = CacheConfig
   { size :: Int
-    -- ^ how many items are allowed in the cache
+  -- ^ how many items are allowed in the cache
   , cacheFilter :: CacheKey -> Bool
-    -- ^ which route to cache
+  -- ^ which route to cache
   }
 
 -- | Route key identidfies the single item for caching
 data CacheKey = CacheKey
-  { inputType :: ByteString  -- ^ value of "Content-Type" header
-  , outputType :: ByteString -- ^ value of "Accept" header
-  , method :: Method -- ^ http method
-  , path :: [Text] -- ^ path to route (includes inlined captures)
+  { inputType :: ByteString
+  -- ^ value of "Content-Type" header
+  , outputType :: ByteString
+  -- ^ value of "Accept" header
+  , method :: Method
+  -- ^ http method
+  , path :: [Text]
+  -- ^ path to route (includes inlined captures)
   }
   deriving (Show, Eq, Ord)
 
 -- | Cache value
 data CacheValue m = CacheValue
-  { captures :: CaptureMap -- ^ extracted capture map from the path
-  , route :: Route m -- ^ route handler
+  { captures :: CaptureMap
+  -- ^ extracted capture map from the path
+  , route :: Route m
+  -- ^ route handler
   }
 
 -- | Route cache
 data RouteCache m = RouteCache
   { cacheFilter :: CacheKey -> Bool
-    -- ^ which route to cache (if True the route is cached)
+  -- ^ which route to cache (if True the route is cached)
   , cache :: AtomicLRU CacheKey (CacheValue m)
-    -- ^ cache map
+  -- ^ cache map
   }
 
 -- | Allocates new cache
diff --git a/test/Test/Server/Counter.hs b/test/Test/Server/Counter.hs
--- a/test/Test/Server/Counter.hs
+++ b/test/Test/Server/Counter.hs
@@ -1,5 +1,3 @@
-{-# LANGUAGE DataKinds #-}
-
 -- | Test case for ReaderT based server
 module Test.Server.Counter (spec) where
 
diff --git a/test/Test/Server/RouteArgs.hs b/test/Test/Server/RouteArgs.hs
--- a/test/Test/Server/RouteArgs.hs
+++ b/test/Test/Server/RouteArgs.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE DataKinds #-}
 {-# LANGUAGE DeriveAnyClass #-}
 
 -- | Tests for various inputs for requests