diff --git a/LICENSE b/LICENSE
--- a/LICENSE
+++ b/LICENSE
@@ -1,4 +1,4 @@
-Copyright (c) 2015, Alp Mestanogullari
+Copyright (c) 2015-2016, Servant Contributors
 
 All rights reserved.
 
diff --git a/example/main.hs b/example/main.hs
--- a/example/main.hs
+++ b/example/main.hs
@@ -20,4 +20,4 @@
 api = Proxy
 
 main :: IO ()
-main = run 8080 (serve api $ mock api)
+main = run 8080 (serve api $ mock api Proxy)
diff --git a/include/overlapping-compat.h b/include/overlapping-compat.h
new file mode 100644
--- /dev/null
+++ b/include/overlapping-compat.h
@@ -0,0 +1,8 @@
+#if __GLASGOW_HASKELL__ >= 710
+#define OVERLAPPABLE_ {-# OVERLAPPABLE #-}
+#define OVERLAPPING_  {-# OVERLAPPING #-}
+#else
+{-# LANGUAGE OverlappingInstances #-}
+#define OVERLAPPABLE_
+#define OVERLAPPING_
+#endif
diff --git a/servant-mock.cabal b/servant-mock.cabal
--- a/servant-mock.cabal
+++ b/servant-mock.cabal
@@ -1,5 +1,5 @@
 name:                servant-mock
-version:             0.4.4.7
+version:             0.5
 synopsis:            Derive a mock server for free from your servant API types
 description:
   Derive a mock server for free from your servant API types
@@ -8,17 +8,17 @@
 homepage:            http://github.com/haskell-servant/servant
 license:             BSD3
 license-file:        LICENSE
-author:              Alp Mestanogullari
-maintainer:          alpmestan@gmail.com
-copyright:           2015 Alp Mestanogullari
+author:              Servant Contributors
+maintainer:          haskell-servant-maintainers@googlegroups.com
+copyright:           2015-2016 Servant Contributors
 category:            Web
 build-type:          Simple
+extra-source-files:  include/*.h
 cabal-version:       >=1.10
 
 flag example
   description: Build the example too
-  manual: True
-  default: False
+  default: True
 
 library
   exposed-modules:
@@ -30,10 +30,11 @@
     servant >= 0.4,
     servant-server >= 0.4,
     transformers >= 0.3 && <0.5,
-    QuickCheck >= 2.8 && <2.9,
+    QuickCheck >= 2.7 && <2.9,
     wai >= 3.0 && <3.3
   hs-source-dirs:      src
   default-language:    Haskell2010
+  include-dirs: include
 
 executable mock-app
   main-is: main.hs
@@ -44,3 +45,24 @@
     buildable: True
   else
     buildable: False
+
+test-suite spec
+  type: exitcode-stdio-1.0
+  ghc-options:
+    -Wall -fno-warn-name-shadowing
+  default-language: Haskell2010
+  hs-source-dirs: test
+  main-is: Spec.hs
+  other-modules:
+    Servant.MockSpec
+  build-depends:
+    base,
+    hspec,
+    hspec-wai,
+    QuickCheck,
+    servant,
+    servant-server,
+    servant-mock,
+    aeson,
+    bytestring-conversion,
+    wai
diff --git a/src/Servant/Mock.hs b/src/Servant/Mock.hs
--- a/src/Servant/Mock.hs
+++ b/src/Servant/Mock.hs
@@ -1,11 +1,16 @@
-{-# LANGUAGE CPP                 #-}
-{-# LANGUAGE DataKinds           #-}
-{-# LANGUAGE FlexibleContexts    #-}
-{-# LANGUAGE FlexibleInstances   #-}
-{-# LANGUAGE ScopedTypeVariables #-}
-{-# LANGUAGE TypeFamilies        #-}
-{-# LANGUAGE TypeOperators       #-}
+{-# LANGUAGE CPP                   #-}
+{-# LANGUAGE DataKinds             #-}
+{-# LANGUAGE FlexibleContexts      #-}
+{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE PolyKinds             #-}
+{-# LANGUAGE ScopedTypeVariables   #-}
+{-# LANGUAGE TypeFamilies          #-}
+{-# LANGUAGE TypeOperators         #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
+
+#include "overlapping-compat.h"
+
 -- |
 -- Module     : Servant.Mock
 -- Copyright  : 2015 Alp Mestanogullari
@@ -69,7 +74,7 @@
 --   than turns them into random-response-generating
 --   request handlers, hence providing an instance for
 --   all the combinators of the core /servant/ library.
-class HasServer api => HasMock api where
+class HasServer api context => HasMock api context where
   -- | Calling this method creates request handlers of
   --   the right type to implement the API described by
   --   @api@ that just generate random response values of
@@ -92,74 +97,75 @@
   --   actually "means" 2 request handlers, of the following types:
   --
   --   @
-  --   getUser :: EitherT ServantErr IO User
-  --   getBook :: EitherT ServantErr IO Book
+  --   getUser :: ExceptT ServantErr IO User
+  --   getBook :: ExceptT ServantErr IO Book
   --   @
   --
   --   So under the hood, 'mock' uses the 'IO' bit to generate
   --   random values of type 'User' and 'Book' every time these
   --   endpoints are requested.
-  mock :: Proxy api -> Server api
+  mock :: Proxy api -> Proxy context -> Server api
 
-instance (HasMock a, HasMock b) => HasMock (a :<|> b) where
-  mock _ = mock (Proxy :: Proxy a) :<|> mock (Proxy :: Proxy b)
+instance (HasMock a context, HasMock b context) => HasMock (a :<|> b) context where
+  mock _ context = mock (Proxy :: Proxy a) context :<|> mock (Proxy :: Proxy b) context
 
-instance (KnownSymbol path, HasMock rest) => HasMock (path :> rest) where
+instance (KnownSymbol path, HasMock rest context) => HasMock (path :> rest) context where
   mock _ = mock (Proxy :: Proxy rest)
 
-instance (KnownSymbol s, FromText a, HasMock rest) => HasMock (Capture s a :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
-
-instance (AllCTUnrender ctypes a, HasMock rest) => HasMock (ReqBody ctypes a :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
-
-instance (KnownSymbol s, FromText a, HasMock rest)
-      => HasMock (QueryParam s a :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
+instance (KnownSymbol s, FromHttpApiData a, HasMock rest context) => HasMock (Capture s a :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (KnownSymbol s, FromText a, HasMock rest)
-      => HasMock (QueryParams s a :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
+instance (AllCTUnrender ctypes a, HasMock rest context) => HasMock (ReqBody ctypes a :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (KnownSymbol s, HasMock rest) => HasMock (QueryFlag s :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
+instance HasMock rest context => HasMock (RemoteHost :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (KnownSymbol s, FromText a, HasMock rest)
-      => HasMock (MatrixParam s a :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
+instance HasMock rest context => HasMock (IsSecure :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (KnownSymbol s, FromText a, HasMock rest)
-      => HasMock (MatrixParams s a :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
+instance HasMock rest context => HasMock (Vault :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (KnownSymbol s, HasMock rest) => HasMock (MatrixFlag s :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
+instance HasMock rest context => HasMock (HttpVersion :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (KnownSymbol h, FromText a, HasMock rest) => HasMock (Header h a :> rest) where
-  mock _ = \_ -> mock (Proxy :: Proxy rest)
+instance (KnownSymbol s, FromHttpApiData a, HasMock rest context)
+      => HasMock (QueryParam s a :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (Arbitrary a, AllCTRender ctypes a) => HasMock (Delete ctypes a) where
-  mock _ = mockArbitrary
+instance (KnownSymbol s, FromHttpApiData a, HasMock rest context)
+      => HasMock (QueryParams s a :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (Arbitrary a, AllCTRender ctypes a) => HasMock (Get ctypes a) where
-  mock _ = mockArbitrary
+instance (KnownSymbol s, HasMock rest context) => HasMock (QueryFlag s :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (Arbitrary a, AllCTRender ctypes a) => HasMock (Patch ctypes a) where
-  mock _ = mockArbitrary
+instance (KnownSymbol h, FromHttpApiData a, HasMock rest context) => HasMock (Header h a :> rest) context where
+  mock _ context = \_ -> mock (Proxy :: Proxy rest) context
 
-instance (Arbitrary a, AllCTRender ctypes a) => HasMock (Post ctypes a) where
-  mock _ = mockArbitrary
+instance (Arbitrary a, KnownNat status, ReflectMethod method, AllCTRender ctypes a)
+    => HasMock (Verb method status ctypes a) context where
+  mock _ _ = mockArbitrary
 
-instance (Arbitrary a, AllCTRender ctypes a) => HasMock (Put ctypes a) where
-  mock _ = mockArbitrary
+instance OVERLAPPING_
+    (GetHeaders (Headers headerTypes a), Arbitrary (HList headerTypes),
+     Arbitrary a, KnownNat status, ReflectMethod method, AllCTRender ctypes a)
+    => HasMock (Verb method status ctypes (Headers headerTypes a)) context where
+  mock _ _ = mockArbitrary
 
-instance HasMock Raw where
-  mock _ = \_ respond -> do
+instance HasMock Raw context where
+  mock _ _ = \_req respond -> do
     bdy <- genBody
     respond $ responseLBS status200 [] bdy
 
     where genBody = pack <$> generate (vector 100 :: Gen [Char])
 
+instance (HasContextEntry context (NamedContext name subContext), HasMock rest subContext) =>
+  HasMock (WithNamedContext name subContext rest) context where
+
+  mock _ _ = mock (Proxy :: Proxy rest) (Proxy :: Proxy subContext)
+
 mockArbitrary :: (MonadIO m, Arbitrary a) => m a
 mockArbitrary = liftIO (generate arbitrary)
 
@@ -174,5 +180,3 @@
 instance (Arbitrary a, Arbitrary (HList hs))
       => Arbitrary (HList (Header h a ': hs)) where
   arbitrary = HCons <$> fmap Header arbitrary <*> arbitrary
-
-
diff --git a/test/Servant/MockSpec.hs b/test/Servant/MockSpec.hs
new file mode 100644
--- /dev/null
+++ b/test/Servant/MockSpec.hs
@@ -0,0 +1,85 @@
+{-# LANGUAGE ConstraintKinds #-}
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveGeneric #-}
+{-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE TypeOperators #-}
+
+module Servant.MockSpec where
+
+import           Data.Aeson as Aeson
+import           Data.ByteString.Conversion.To
+import           Data.Proxy
+import           Data.String
+import           GHC.Generics
+import           Network.Wai
+import           Servant.API
+import           Test.Hspec hiding (pending)
+import           Test.Hspec.Wai
+import           Test.QuickCheck
+
+import           Servant
+import           Servant.API.Internal.Test.ComprehensiveAPI
+import           Servant.Mock
+
+-- This declaration simply checks that all instances are in place.
+_ = mock comprehensiveAPI (Proxy :: Proxy '[NamedContext "foo" '[]])
+
+data Body
+  = Body
+  | ArbitraryBody
+  deriving (Generic)
+
+instance ToJSON Body
+
+instance Arbitrary Body where
+  arbitrary = return ArbitraryBody
+
+data TestHeader
+  = TestHeader
+  | ArbitraryHeader
+  deriving (Show)
+
+instance ToByteString TestHeader where
+  builder = fromString . show
+
+instance Arbitrary TestHeader where
+  arbitrary = return ArbitraryHeader
+
+spec :: Spec
+spec = do
+  describe "mock" $ do
+    context "Get" $ do
+      let api :: Proxy (Get '[JSON] Body)
+          api = Proxy
+          app = serve api (mock api Proxy)
+      with (return app) $ do
+        it "serves arbitrary response bodies" $ do
+          get "/" `shouldRespondWith` 200{
+            matchBody = Just $ Aeson.encode ArbitraryBody
+          }
+
+    context "response headers" $ do
+      let withHeader :: Proxy (Get '[JSON] (Headers '[Header "foo" TestHeader] Body))
+          withHeader = Proxy
+          withoutHeader :: Proxy (Get '[JSON] (Headers '[] Body))
+          withoutHeader = Proxy
+          toApp :: (HasMock api '[]) => Proxy api -> IO Application
+          toApp api = return $ serve api (mock api (Proxy :: Proxy '[]))
+      with (toApp withHeader) $ do
+        it "serves arbitrary response bodies" $ do
+          get "/" `shouldRespondWith` 200{
+            matchHeaders = return $ MatchHeader $ \ h ->
+             if h == [("Content-Type", "application/json"), ("foo", "ArbitraryHeader")]
+                then Nothing
+                else Just ("headers not correct\n")
+          }
+
+      with (toApp withoutHeader) $ do
+        it "works for no additional headers" $ do
+          get "/" `shouldRespondWith` 200{
+            matchHeaders = return $ MatchHeader $ \ h ->
+             if h == [("Content-Type", "application/json")]
+                then Nothing
+                else Just ("headers not correct\n")
+          }
diff --git a/test/Spec.hs b/test/Spec.hs
new file mode 100644
--- /dev/null
+++ b/test/Spec.hs
@@ -0,0 +1,1 @@
+{-# OPTIONS_GHC -F -pgmF hspec-discover #-}