diff --git a/servant-client/src/Servant/Client.hs b/servant-client/src/Servant/Client.hs
index e09b138d..67b6c8de 100644
--- a/servant-client/src/Servant/Client.hs
+++ b/servant-client/src/Servant/Client.hs
@@ -16,7 +16,6 @@
 module Servant.Client
   ( client
   , HasClient(..)
-  , Client
   , ServantError(..)
   , module Servant.Common.BaseUrl
   ) where
diff --git a/servant-docs/src/Servant/Docs/Internal.hs b/servant-docs/src/Servant/Docs/Internal.hs
index 88f512d8..35671592 100644
--- a/servant-docs/src/Servant/Docs/Internal.hs
+++ b/servant-docs/src/Servant/Docs/Internal.hs
@@ -660,7 +660,11 @@ instance HasDocs Delete where
           action' = action & response.respBody .~ []
                            & response.respStatus .~ 204
 
-instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
+instance
+#if MIN_VERSION_base(4,8,0)
+         {-# OVERLAPPABLe #-}
+#endif
+        (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
     => HasDocs (Get cts a) where
   docsFor Proxy (endpoint, action) =
     single endpoint' action'
@@ -671,7 +675,11 @@ instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
           t = Proxy :: Proxy cts
           p = Proxy :: Proxy a
 
-instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts
+instance
+#if MIN_VERSION_base(4,8,0)
+         {-# OVERLAPPING #-}
+#endif
+        (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts
          , AllHeaderSamples ls , GetHeaders (HList ls) )
     => HasDocs (Get cts (Headers ls a)) where
   docsFor Proxy (endpoint, action) =
@@ -694,7 +702,11 @@ instance (KnownSymbol sym, HasDocs sublayout)
           action' = over headers (|> headername) action
           headername = pack $ symbolVal (Proxy :: Proxy sym)
 
-instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
+instance
+#if MIN_VERSION_base(4,8,0)
+         {-# OVERLAPPABLE #-}
+#endif
+        (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
     => HasDocs (Post cts a) where
   docsFor Proxy (endpoint, action) =
     single endpoint' action'
@@ -706,7 +718,11 @@ instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
           t = Proxy :: Proxy cts
           p = Proxy :: Proxy a
 
-instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts
+instance
+#if MIN_VERSION_base(4,8,0)
+         {-# OVERLAPPING #-}
+#endif
+         (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts
          , AllHeaderSamples ls , GetHeaders (HList ls) )
     => HasDocs (Post cts (Headers ls a)) where
   docsFor Proxy (endpoint, action) =
@@ -721,7 +737,11 @@ instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts
           t = Proxy :: Proxy cts
           p = Proxy :: Proxy a
 
-instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
+instance
+#if MIN_VERSION_base(4,8,0)
+         {-# OVERLAPPABLE #-}
+#endif
+        (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
     => HasDocs (Put cts a) where
   docsFor Proxy (endpoint, action) =
     single endpoint' action'
@@ -733,7 +753,11 @@ instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts)
           t = Proxy :: Proxy cts
           p = Proxy :: Proxy a
 
-instance (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts
+instance
+#if MIN_VERSION_base(4,8,0)
+         {-# OVERLAPPING #-}
+#endif
+        (ToSample a b, IsNonEmpty cts, AllMimeRender cts b, SupportedTypes cts
          , AllHeaderSamples ls , GetHeaders (HList ls) )
     => HasDocs (Put cts (Headers ls a)) where
   docsFor Proxy (endpoint, action) =
diff --git a/servant-examples/auth-combinator/auth-combinator.hs b/servant-examples/auth-combinator/auth-combinator.hs
index 3277c97e..c6373fe1 100644
--- a/servant-examples/auth-combinator/auth-combinator.hs
+++ b/servant-examples/auth-combinator/auth-combinator.hs
@@ -26,7 +26,7 @@ isGoodCookie = return . (== "good password")
 data AuthProtected
 
 instance HasServer rest => HasServer (AuthProtected :> rest) where
-  type ServerT' (AuthProtected :> rest) m = ServerT' rest m
+  type ServerT (AuthProtected :> rest) m = ServerT rest m
 
   route Proxy a request respond =
     case lookup "Cookie" (requestHeaders request) of
@@ -75,4 +75,4 @@ $ curl -H "Cookie: good password" http://localhost:8080/private
 [{"ssshhh":"this is a secret"}]
 $ curl -H "Cookie: bad password" http://localhost:8080/private
 Invalid cookie.
--}
\ No newline at end of file
+-}
diff --git a/servant-jquery/test/Servant/JQuerySpec/CustomHeaders.hs b/servant-jquery/test/Servant/JQuerySpec/CustomHeaders.hs
index 95cf4487..4480d44c 100644
--- a/servant-jquery/test/Servant/JQuerySpec/CustomHeaders.hs
+++ b/servant-jquery/test/Servant/JQuerySpec/CustomHeaders.hs
@@ -22,7 +22,7 @@ data Authorization (sym :: Symbol) a
 
 instance (KnownSymbol sym, HasJQ sublayout)
     => HasJQ (Authorization sym a :> sublayout) where
-    type JQ' (Authorization sym a :> sublayout) = JQ' sublayout
+    type JQ (Authorization sym a :> sublayout) = JQ sublayout
 
     jqueryFor Proxy req = jqueryFor (Proxy :: Proxy sublayout) $
         req & reqHeaders <>~ [ ReplaceHeaderArg "Authorization" $
@@ -35,7 +35,7 @@ data MyLovelyHorse a
 
 instance (HasJQ sublayout)
     => HasJQ (MyLovelyHorse a :> sublayout) where
-    type JQ' (MyLovelyHorse a :> sublayout) = JQ' sublayout
+    type JQ (MyLovelyHorse a :> sublayout) = JQ sublayout
 
     jqueryFor Proxy req = jqueryFor (Proxy :: Proxy sublayout) $
         req & reqHeaders <>~ [ ReplaceHeaderArg "X-MyLovelyHorse" tpl ]
@@ -47,7 +47,7 @@ data WhatsForDinner a
 
 instance (HasJQ sublayout)
     => HasJQ (WhatsForDinner a :> sublayout) where
-    type JQ' (WhatsForDinner a :> sublayout) = JQ' sublayout
+    type JQ (WhatsForDinner a :> sublayout) = JQ sublayout
 
     jqueryFor Proxy req = jqueryFor (Proxy :: Proxy sublayout) $
         req & reqHeaders <>~ [ ReplaceHeaderArg "X-WhatsForDinner" tpl ]
diff --git a/servant-lucid/servant-lucid.cabal b/servant-lucid/servant-lucid.cabal
index b2d02316..7088003d 100644
--- a/servant-lucid/servant-lucid.cabal
+++ b/servant-lucid/servant-lucid.cabal
@@ -20,7 +20,7 @@ library
   exposed-modules:     Servant.HTML.Lucid
   -- other-modules:
   -- other-extensions:
-  build-depends:       base >=4.7 && <4.8
+  build-depends:       base >=4.7 && <5
                      , http-media
                      , lucid
                      , servant
diff --git a/servant-server/src/Servant/Server/Internal/Enter.hs b/servant-server/src/Servant/Server/Internal/Enter.hs
index e408087a..a8a904d6 100644
--- a/servant-server/src/Servant/Server/Internal/Enter.hs
+++ b/servant-server/src/Servant/Server/Internal/Enter.hs
@@ -3,7 +3,6 @@
 {-# LANGUAGE FlexibleInstances      #-}
 {-# LANGUAGE FunctionalDependencies #-}
 {-# LANGUAGE MultiParamTypeClasses  #-}
-{-# LANGUAGE OverlappingInstances   #-}
 {-# LANGUAGE RankNTypes             #-}
 {-# LANGUAGE ScopedTypeVariables    #-}
 {-# LANGUAGE TypeFamilies           #-}
@@ -11,7 +10,9 @@
 {-# LANGUAGE UndecidableInstances   #-}
 module Servant.Server.Internal.Enter where
 
+#if !MIN_VERSION_base(4,8,0)
 import           Control.Applicative
+#endif
 import qualified Control.Category            as C
 #if MIN_VERSION_mtl(2,2,1)
 import           Control.Monad.Except
diff --git a/servant/src/Servant/API.hs b/servant/src/Servant/API.hs
index a7912564..034be7a2 100644
--- a/servant/src/Servant/API.hs
+++ b/servant/src/Servant/API.hs
@@ -54,7 +54,6 @@ module Servant.API (
   -- | Type-safe internal URIs
   ) where
 
-import           Data.Proxy                  (Proxy (..))
 import           Servant.API.Alternative     ((:<|>) (..))
 import           Servant.API.Capture         (Capture)
 import           Servant.API.ContentTypes    (Accept (..), FormUrlEncoded,