diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,12 @@
+0.1.0
+=====
+
+  * Removed the `message` field from the `Sys` type.
+    It was some internal parameter and might be absent.
+
+  * Require servant-client >= 0.16 (for `ClientError` instead of `ServantError`).
+
+
 0.0.0
 =====
 
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@
 ============
 
 OpenWeatherMap is written in Haskell with [GHC](http://www.haskell.org/ghc/).
-All required Haskell libraries are listed in [openweathermap.cabal](ldapply.cabal).
+All required Haskell libraries are listed in [openweathermap.cabal](openweathermap.cabal).
 Use [cabal-install](http://www.haskell.org/haskellwiki/Cabal-Install) to fetch
 and build all pre-requisites automatically.
 
@@ -36,7 +36,7 @@
   -h,--help                Show this help text
 
 ```
-By default, `openweathermap` read the API key
+By default, `openweathermap` reads the API key
 from the `$XDG_CONFIG_HOME/openweathermap/key` file, where
 [`$XDG_CONFIG_HOME`](https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html)
 is typically `~/.config` on Linux systems.
diff --git a/Setup.hs b/Setup.hs
deleted file mode 100644
--- a/Setup.hs
+++ /dev/null
@@ -1,2 +0,0 @@
-import Distribution.Simple
-main = defaultMain
diff --git a/cmd/Main.hs b/cmd/Main.hs
--- a/cmd/Main.hs
+++ b/cmd/Main.hs
@@ -1,8 +1,8 @@
 {-# LANGUAGE LambdaCase #-}
 
-module Main (
-  main
-) where
+module Main
+  ( main
+  ) where
 
 import Control.Monad (when)
 import Data.List (intercalate)
@@ -11,9 +11,24 @@
 import System.Exit (die)
 import System.IO (IOMode(ReadMode), hGetLine, hPrint, stderr, withFile)
 
-import Options.Applicative (
-    (<**>), (<|>), Parser, auto, execParser, fullDesc, header, help, helper,
-    info, long, metavar, option, optional, short, strOption, switch
+import Options.Applicative
+  ( Parser
+  , (<**>)
+  , (<|>)
+  , auto
+  , execParser
+  , fullDesc
+  , header
+  , help
+  , helper
+  , info
+  , long
+  , metavar
+  , option
+  , optional
+  , short
+  , strOption
+  , switch
   )
 import System.Directory (createDirectoryIfMissing)
 import System.Environment.XDG.BaseDir (getUserConfigDir, getUserConfigFile)
@@ -33,22 +48,17 @@
 parseLocation :: Parser Client.Location
 parseLocation = byName <|> byCoord
   where
-    byName = Client.Name <$> strOption
-      (  long "city"
-      <> short 'c'
-      <> metavar "CITY"
-      <> help "City name" )
-
-    byCoord = Client.Coord
-      <$> option auto
-        (  long "lat"
-        <> metavar "NUM"
-        <> help "Latitude in decimal degrees" )
-      <*> option auto
-        (  long "lon"
-        <> metavar "NUM"
-        <> help "Longitude in decimal degrees" )
-
+    byName =
+      Client.Name <$>
+      strOption (long "city" <> short 'c' <> metavar "CITY" <> help "City name")
+    byCoord =
+      Client.Coord <$>
+      option
+        auto
+        (long "lat" <> metavar "NUM" <> help "Latitude in decimal degrees") <*>
+      option
+        auto
+        (long "lon" <> metavar "NUM" <> help "Longitude in decimal degrees")
 
 data ApiKey
   = ApiKeyFile FilePath
@@ -57,18 +67,15 @@
 parseApiKey :: Parser ApiKey
 parseApiKey = fromFile <|> inCmdLine
   where
-    fromFile = ApiKeyFile <$> strOption
-      (  long "api-key-file"
-      <> short 'K'
-      <> metavar "APIKEYFILE"
-      <> help "Read API key from this file" )
-
-    inCmdLine = ApiKey <$> strOption
-      (  long "api-key"
-      <> short 'k'
-      <> metavar "APIKEY"
-      <> help "API key" )
-
+    fromFile =
+      ApiKeyFile <$>
+      strOption
+        (long "api-key-file" <> short 'K' <> metavar "APIKEYFILE" <>
+         help "Read API key from this file")
+    inCmdLine =
+      ApiKey <$>
+      strOption
+        (long "api-key" <> short 'k' <> metavar "APIKEY" <> help "API key")
 
 data Config = Config
   { apikey :: Maybe ApiKey
@@ -77,10 +84,9 @@
   }
 
 parseConfig :: Parser Config
-parseConfig = Config
-          <$> optional parseApiKey
-          <*> parseLocation
-          <*> switch (long "debug" <> short 'd' <> help "Enable debug")
+parseConfig =
+  Config <$> optional parseApiKey <*> parseLocation <*>
+  switch (long "debug" <> short 'd' <> help "Enable debug")
 
 getApiKey :: Maybe ApiKey -> IO String
 getApiKey (Just (ApiKey key)) = return key
@@ -89,16 +95,18 @@
   createDirectoryIfMissing True =<< getUserConfigDir appName
   getUserConfigFile appName "key" >>= getApiKey . Just . ApiKeyFile
 
-
 showLocation :: CurrentWeather.CurrentWeather -> String
 showLocation w = city ++ maybe "" ("," ++) country ++ " " ++ coords
   where
     name = CurrentWeather.name w
     coord = CurrentWeather.coord w
     country = Sys.country . CurrentWeather.sys $ w
-    city = if name /= "" then name else "<unknown>"
-    coords = "("++ show (Coord.lat coord) ++ "°, "
-                ++ show (Coord.lon coord) ++ "°)"
+    city =
+      if name /= ""
+        then name
+        else "<unknown>"
+    coords =
+      "(" ++ show (Coord.lat coord) ++ "°, " ++ show (Coord.lon coord) ++ "°)"
 
 showWeather :: [Weather.Weather] -> String
 showWeather w = intercalate "," $ Weather.main <$> w
@@ -125,7 +133,7 @@
     speed = round . Wind.speed $ w
     deg = Wind.deg w
     --     [ "N", "NE", "E", "SE", "S", "SW", "W", "NW" ]
-    dirs = [ "↓", "↙",  "←", "↖",  "↑", "↗",  "→", "↘"  ]
+    dirs = ["↓", "↙", "←", "↖", "↑", "↗", "→", "↘"]
     l = length dirs
     sector = round $ (deg * fromIntegral l) / 360.0
     dir = dirs !! (sector `rem` l)
@@ -138,10 +146,14 @@
     tmin :: Int
     tmax = round . k2c . Main.temp_max $ m
     tmin = round . k2c . Main.temp_min $ m
-    show' t = if t > 0 then "+" ++ show t else show t
-    temp = if tmax /= tmin
-           then show' tmin ++ ".." ++ show' tmax
-           else show' tmin
+    show' t =
+      if t > 0
+        then "+" ++ show t
+        else show t
+    temp =
+      if tmax /= tmin
+        then show' tmin ++ ".." ++ show' tmax
+        else show' tmin
 
 printWeather :: CurrentWeather.CurrentWeather -> IO ()
 printWeather w = putStrLn out
@@ -150,15 +162,23 @@
     place = showLocation w
     mainw = CurrentWeather.main w
     wind = CurrentWeather.wind w
-    out = place ++ ": " ++ intercalate ",  "
-      [ weather, showHumidity mainw, showPressure mainw, showTemp mainw,
-        showWind wind ]
+    out =
+      place ++
+      ": " ++
+      intercalate
+        ",  "
+        [ weather
+        , showHumidity mainw
+        , showPressure mainw
+        , showTemp mainw
+        , showWind wind
+        ]
 
 run :: Config -> IO ()
 run cfg = do
   appid <- getApiKey . apikey $ cfg
   Client.getWeather appid (location cfg) >>= \case
-    Left err      -> die $ show err
+    Left err -> die $ show err
     Right weather -> do
       when (debug cfg) $ hPrint stderr weather
       printWeather weather
@@ -167,7 +187,7 @@
 main = run =<< execParser opts
   where
     opts = info (parseConfig <**> helper) (fullDesc <> header desc)
-    desc = "openweathermap "
-        ++ showVersion version
-        ++ " - command-line client for https://openweathermap.org/api"
-
+    desc =
+      "openweathermap " ++
+      showVersion version ++
+      " - command-line client for https://openweathermap.org/api"
diff --git a/lib/Web/OpenWeatherMap/API.hs b/lib/Web/OpenWeatherMap/API.hs
--- a/lib/Web/OpenWeatherMap/API.hs
+++ b/lib/Web/OpenWeatherMap/API.hs
@@ -2,44 +2,37 @@
 Direct API functions.
 For API key (a.k.a appid) refer to <http://openweathermap.org/appid>.
 -}
-
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE TypeOperators #-}
 
-module Web.OpenWeatherMap.API (
-  weatherByName,
-  weatherByCoord
-) where
+module Web.OpenWeatherMap.API
+  ( weatherByName
+  , weatherByCoord
+  ) where
 
 import Data.Proxy (Proxy(..))
 
-import Servant.API ((:>), (:<|>)(..), JSON, Get, QueryParam)
-import Servant.Client (client)
-import Servant.Common.Req (ClientM)
+import Servant.API ((:<|>)(..), (:>), Get, JSON, QueryParam)
+import Servant.Client (ClientM, client)
 
 import Web.OpenWeatherMap.Types.CurrentWeather (CurrentWeather)
 
+type GetCurrentWeather = AppId :> Get '[ JSON] CurrentWeather
 
-type GetCurrentWeather = AppId :> Get '[JSON] CurrentWeather
 type AppId = QueryParam "appid" String
 
 type API
-     = "weather" :> QueryParam "q" String :> GetCurrentWeather
-  :<|> "weather" :> QueryParam "lat" Double :> QueryParam "lon" Double
-                 :> GetCurrentWeather
+   = "weather" :> QueryParam "q" String :> GetCurrentWeather :<|> "weather" :> QueryParam "lat" Double :> QueryParam "lon" Double :> GetCurrentWeather
 
 -- | Request current weather in the city.
-weatherByName
-  :: Maybe String  -- ^ City name, e. g. \"Moscow\" or \"Moscow,ru\".
-  -> Maybe String  -- ^ API key.
+weatherByName ::
+     Maybe String -- ^ City name, e. g. \"Moscow\" or \"Moscow,ru\".
+  -> Maybe String -- ^ API key.
   -> ClientM CurrentWeather
-
 -- | Request current weather at the geographic coordinates (in decimal degrees).
-weatherByCoord
-  :: Maybe Double  -- ^ Latitude, e. g. 55.7522200 for Moscow.
-  -> Maybe Double  -- ^ Longitude, e. g. 37.6155600 for Moscow.
-  -> Maybe String  -- ^ API key.
+weatherByCoord ::
+     Maybe Double -- ^ Latitude, e. g. 55.7522200 for Moscow.
+  -> Maybe Double -- ^ Longitude, e. g. 37.6155600 for Moscow.
+  -> Maybe String -- ^ API key.
   -> ClientM CurrentWeather
-
 weatherByName :<|> weatherByCoord = client (Proxy :: Proxy API)
-
diff --git a/lib/Web/OpenWeatherMap/Client.hs b/lib/Web/OpenWeatherMap/Client.hs
--- a/lib/Web/OpenWeatherMap/Client.hs
+++ b/lib/Web/OpenWeatherMap/Client.hs
@@ -1,38 +1,42 @@
 {-|
 High-level client functions perfoming requests to OpenWeatherMap API.
 -}
-module Web.OpenWeatherMap.Client (
-  Location(..),
-  getWeather
-) where
+module Web.OpenWeatherMap.Client
+  ( Location(..)
+  , getWeather
+  ) where
 
-import Network.HTTP.Client (newManager, defaultManagerSettings)
-import Servant.Client (ClientEnv(..), runClientM, ServantError)
-import Servant.Common.BaseUrl (BaseUrl(..), Scheme(..))
-import Servant.Common.Req (ClientM)
+import Network.HTTP.Client (defaultManagerSettings, newManager)
+import Servant.Client
+  ( BaseUrl(BaseUrl)
+  , ClientEnv
+  , ClientError
+  , ClientM
+  , Scheme(Http)
+  , mkClientEnv
+  , runClientM
+  )
 
-import Web.OpenWeatherMap.Types.CurrentWeather (CurrentWeather)
 import qualified Web.OpenWeatherMap.API as API
-
+import Web.OpenWeatherMap.Types.CurrentWeather (CurrentWeather)
 
 -- | Various way to specify location.
 data Location
-  = Name String          -- ^ City name.
-  | Coord Double Double  -- ^ Geographic coordinates: latitude and longitude.
-
+  = Name String -- ^ City name.
+  | Coord Double
+          Double -- ^ Geographic coordinates: latitude and longitude.
 
 -- | Make a request to OpenWeatherMap API
 --   and return current weather in given location.
-getWeather
-  :: String -- ^ API key.
+getWeather ::
+     String -- ^ API key.
   -> Location
-  -> IO (Either ServantError CurrentWeather)
-getWeather appid loc =
-  defaultEnv >>= runClientM (api loc appid)
+  -> IO (Either ClientError CurrentWeather)
+getWeather appid loc = defaultEnv >>= runClientM (api loc appid)
 
-api
-  :: Location
-  -> String                  -- ^ API key.
+api ::
+     Location
+  -> String -- ^ API key.
   -> ClientM CurrentWeather
 api (Name city) = API.weatherByName (Just city) . Just
 api (Coord lat lon) = API.weatherByCoord (Just lat) (Just lon) . Just
@@ -40,10 +44,9 @@
 defaultEnv :: IO ClientEnv
 defaultEnv = do
   manager <- newManager defaultManagerSettings
-  return $ ClientEnv manager baseUrl
+  return $ mkClientEnv manager baseUrl
 
 -- XXX openweathermap.org does not support HTTPS,
 -- XXX appid is passed in clear text. Oops.
 baseUrl :: BaseUrl
 baseUrl = BaseUrl Http "api.openweathermap.org" 80 "/data/2.5"
-
diff --git a/lib/Web/OpenWeatherMap/Types/Clouds.hs b/lib/Web/OpenWeatherMap/Types/Clouds.hs
--- a/lib/Web/OpenWeatherMap/Types/Clouds.hs
+++ b/lib/Web/OpenWeatherMap/Types/Clouds.hs
@@ -1,16 +1,14 @@
 {-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DeriveGeneric #-}
 
-module Web.OpenWeatherMap.Types.Clouds (
-  Clouds(..)
-) where
+module Web.OpenWeatherMap.Types.Clouds
+  ( Clouds(..)
+  ) where
 
 import GHC.Generics (Generic)
 
 import Data.Aeson (FromJSON)
- 
 
 data Clouds = Clouds
   { all :: Double
   } deriving (Show, Generic, FromJSON)
-
diff --git a/lib/Web/OpenWeatherMap/Types/Coord.hs b/lib/Web/OpenWeatherMap/Types/Coord.hs
--- a/lib/Web/OpenWeatherMap/Types/Coord.hs
+++ b/lib/Web/OpenWeatherMap/Types/Coord.hs
@@ -1,17 +1,15 @@
 {-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DeriveGeneric #-}
 
-module Web.OpenWeatherMap.Types.Coord (
-  Coord(..)
-) where
+module Web.OpenWeatherMap.Types.Coord
+  ( Coord(..)
+  ) where
 
 import GHC.Generics (Generic)
 
 import Data.Aeson (FromJSON)
 
-
 data Coord = Coord
   { lon :: Double
   , lat :: Double
   } deriving (Show, Generic, FromJSON)
-
diff --git a/lib/Web/OpenWeatherMap/Types/CurrentWeather.hs b/lib/Web/OpenWeatherMap/Types/CurrentWeather.hs
--- a/lib/Web/OpenWeatherMap/Types/CurrentWeather.hs
+++ b/lib/Web/OpenWeatherMap/Types/CurrentWeather.hs
@@ -1,12 +1,12 @@
 {-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DeriveGeneric #-}
 
-module Web.OpenWeatherMap.Types.CurrentWeather (
-  CurrentWeather(..)
-) where
+module Web.OpenWeatherMap.Types.CurrentWeather
+  ( CurrentWeather(..)
+  ) where
 
-import Prelude hiding (id)
 import GHC.Generics (Generic)
+import Prelude hiding (id)
 
 import Data.Aeson (FromJSON)
 
@@ -32,4 +32,3 @@
   , name :: String
   , cod :: Int
   } deriving (Show, Generic, FromJSON)
-
diff --git a/lib/Web/OpenWeatherMap/Types/Main.hs b/lib/Web/OpenWeatherMap/Types/Main.hs
--- a/lib/Web/OpenWeatherMap/Types/Main.hs
+++ b/lib/Web/OpenWeatherMap/Types/Main.hs
@@ -1,16 +1,16 @@
 {-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DeriveGeneric #-}
 
-module Web.OpenWeatherMap.Types.Main (
-  Main(..)
-) where
+module Web.OpenWeatherMap.Types.Main
+  ( Main(..)
+  ) where
 
 import GHC.Generics (Generic)
 
 import Data.Aeson (FromJSON)
- 
 
 {-# ANN module "HLint: ignore Use camelCase" #-}
+
 data Main = Main
   { temp :: Double
   , pressure :: Double
@@ -20,4 +20,3 @@
   , sea_level :: Maybe Double
   , grnd_level :: Maybe Double
   } deriving (Show, Generic, FromJSON)
-
diff --git a/lib/Web/OpenWeatherMap/Types/Sys.hs b/lib/Web/OpenWeatherMap/Types/Sys.hs
--- a/lib/Web/OpenWeatherMap/Types/Sys.hs
+++ b/lib/Web/OpenWeatherMap/Types/Sys.hs
@@ -1,19 +1,16 @@
 {-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DeriveGeneric #-}
 
-module Web.OpenWeatherMap.Types.Sys (
-  Sys(..)
-) where
+module Web.OpenWeatherMap.Types.Sys
+  ( Sys(..)
+  ) where
 
 import GHC.Generics (Generic)
 
 import Data.Aeson (FromJSON)
- 
 
 data Sys = Sys
-  { message :: Double
-  , country :: Maybe String
+  { country :: Maybe String
   , sunrise :: Int
   , sunset :: Int
   } deriving (Show, Generic, FromJSON)
-
diff --git a/lib/Web/OpenWeatherMap/Types/Weather.hs b/lib/Web/OpenWeatherMap/Types/Weather.hs
--- a/lib/Web/OpenWeatherMap/Types/Weather.hs
+++ b/lib/Web/OpenWeatherMap/Types/Weather.hs
@@ -1,19 +1,17 @@
 {-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DeriveGeneric #-}
 
-module Web.OpenWeatherMap.Types.Weather (
-  Weather(..)
-) where
+module Web.OpenWeatherMap.Types.Weather
+  ( Weather(..)
+  ) where
 
 import GHC.Generics (Generic)
 
 import Data.Aeson (FromJSON)
 
-
 data Weather = Weather
   { id :: Int
   , main :: String
   , description :: String
   , icon :: String
   } deriving (Show, Generic, FromJSON)
-
diff --git a/lib/Web/OpenWeatherMap/Types/Wind.hs b/lib/Web/OpenWeatherMap/Types/Wind.hs
--- a/lib/Web/OpenWeatherMap/Types/Wind.hs
+++ b/lib/Web/OpenWeatherMap/Types/Wind.hs
@@ -1,17 +1,15 @@
 {-# LANGUAGE DeriveAnyClass #-}
 {-# LANGUAGE DeriveGeneric #-}
 
-module Web.OpenWeatherMap.Types.Wind (
-  Wind(..)
-) where
+module Web.OpenWeatherMap.Types.Wind
+  ( Wind(..)
+  ) where
 
 import GHC.Generics (Generic)
 
 import Data.Aeson (FromJSON)
- 
 
 data Wind = Wind
   { speed :: Double
   , deg :: Double
   } deriving (Show, Generic, FromJSON)
-
diff --git a/openweathermap.cabal b/openweathermap.cabal
--- a/openweathermap.cabal
+++ b/openweathermap.cabal
@@ -1,5 +1,5 @@
 name: openweathermap
-version: 0.0.0
+version: 0.1.0
 synopsis: Access data at OpenWeatherMap
 description: Client library and command-line utility to access
   OpenWeatherMap https://openweathermap.org
@@ -11,7 +11,7 @@
 category: Web
 build-type: Simple
 extra-source-files: README.md ChangeLog.md
-cabal-version: >= 1.20
+cabal-version: 1.20
 
 source-repository head
   type: git
@@ -30,7 +30,7 @@
     , aeson
     , http-client
     , servant
-    , servant-client >= 0.9
+    , servant-client >= 0.16
   exposed-modules:
      Web.OpenWeatherMap.API
      Web.OpenWeatherMap.Client