diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,3 +1,8 @@
+[![Build Status](https://travis-ci.org/arowM/haskell-google-server-api.svg?branch=master)](https://travis-ci.org/arowM/haskell-google-server-api)
+[![Hackage](https://img.shields.io/hackage/v/haskell-google-server-api.svg)](https://hackage.haskell.org/package/google-server-api)
+[![Stackage LTS](http://stackage.org/package/haskell-google-server-api/badge/lts)](http://stackage.org/lts/package/google-server-api)
+[![Stackage Nightly](http://stackage.org/package/haskell-google-server-api/badge/nightly)](http://stackage.org/nightly/package/google-server-api)
+
 # google-server-api
 
 This library provides functions to use [Google APIs for server to server applications](https://developers.google.com/identity/protocols/OAuth2ServiceAccount).
diff --git a/google-server-api.cabal b/google-server-api.cabal
--- a/google-server-api.cabal
+++ b/google-server-api.cabal
@@ -1,5 +1,5 @@
 name:                google-server-api
-version:             0.1.0.1
+version:             0.2.0.0
 synopsis:            Google APIs for server to server applications
 description:
   This library provides a way to use Google API for server to server applications.
@@ -33,7 +33,6 @@
                      , monad-control >= 1.0
                      , monad-logger >= 0.3
                      , mtl >= 2.2
-                     , read-env-var >= 1.0
                      , RSA >= 2.3
                      , servant >= 0.1
                      , servant-client >= 0.2
diff --git a/src/Google/Client.hs b/src/Google/Client.hs
--- a/src/Google/Client.hs
+++ b/src/Google/Client.hs
@@ -156,6 +156,8 @@
 toBearer :: Response.Token -> Bearer
 toBearer Response.Token {accessToken} = Bearer $ "Bearer " <> accessToken
 
+{- | Convert `ServantError` to arbitrary error type.
+-}
 run ::
      forall r m a e.
      ( HasHttpManager r
@@ -163,14 +165,13 @@
      , MonadError e m
      , MonadLogger m
      , MonadReader r m
-     , Show e
      )
   => e
-  -> ReaderT r (ExceptT e IO) a
+  -> ReaderT r (ExceptT ServantError IO) a
   -> m a
 run err m = either doGoogleErr pure =<< run' m
   where
-    doGoogleErr :: forall x. e -> m x
+    doGoogleErr :: forall x. ServantError -> m x
     doGoogleErr googleErr = do
       $(logError) $ "Got error response from google API: " <> tshow googleErr
       throwError err