diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 0.3.0.1
+
+- Use Authorization header (44c3cf1)
+
 # 0.1.0
 
 ## Methods
diff --git a/slack-web.cabal b/slack-web.cabal
--- a/slack-web.cabal
+++ b/slack-web.cabal
@@ -1,5 +1,5 @@
 name: slack-web
-version: 0.3.0.0
+version: 0.3.0.1
 
 build-type: Simple
 cabal-version: 1.20
diff --git a/src/Web/Slack.hs b/src/Web/Slack.hs
--- a/src/Web/Slack.hs
+++ b/src/Web/Slack.hs
@@ -56,11 +56,11 @@
 import Control.Monad.Reader
 
 -- servant
-import Servant.API
+import Servant.API hiding (addHeader)
 
 -- servant-client
 import Servant.Client hiding (Response, baseUrl)
-import Servant.Client.Core (Request, appendToQueryString)
+import Servant.Client.Core (Request, addHeader)
 
 -- slack-web
 import qualified Web.Slack.Api as Api
@@ -399,7 +399,7 @@
   -> Request
   -> Request
 authenticateReq token =
-  appendToQueryString "token" (Just token)
+  addHeader "Authorization" $ "Bearer " <> token
 
 
 -- |