diff --git a/Data/GraphQL.hs b/Data/GraphQL.hs
index dfe9362..dd411e5 100644
--- a/Data/GraphQL.hs
+++ b/Data/GraphQL.hs
@@ -19,7 +19,7 @@ import Data.GraphQL.Error
 --   executed according to the given 'Schema'.
 --
 --   Returns the response as an @Aeson.@'Aeson.Value'.
-graphql :: (Alternative m, Monad m) => Schema m -> Text -> m Aeson.Value
+graphql :: Alternative m => Schema m -> Text -> m Aeson.Value
 graphql = flip graphqlSubs $ const Nothing
 
 -- | Takes a 'Schema', a variable substitution function and text
@@ -28,7 +28,7 @@ graphql = flip graphqlSubs $ const Nothing
 --   query and the query is then executed according to the given 'Schema'.
 --
 --   Returns the response as an @Aeson.@'Aeson.Value'.
-graphqlSubs :: (Alternative m, Monad m) => Schema m -> Subs -> Text -> m Aeson.Value
+graphqlSubs :: Alternative m => Schema m -> Subs -> Text -> m Aeson.Value
 graphqlSubs schema f =
     either parseError (execute schema f)
   . Attoparsec.parseOnly document
diff --git a/Data/GraphQL/AST.hs b/Data/GraphQL/AST.hs
index 99eaa79..98bbe9f 100644
--- a/Data/GraphQL/AST.hs
+++ b/Data/GraphQL/AST.hs
@@ -158,7 +158,7 @@ data InterfaceTypeDefinition = InterfaceTypeDefinition Name [FieldDefinition]
 data UnionTypeDefinition = UnionTypeDefinition Name [NamedType]
                            deriving (Eq,Show)
 
-data ScalarTypeDefinition = ScalarTypeDefinition Name
+newtype ScalarTypeDefinition = ScalarTypeDefinition Name
                             deriving (Eq,Show)
 
 data EnumTypeDefinition = EnumTypeDefinition Name [EnumValueDefinition]
diff --git a/Data/GraphQL/Encoder.hs b/Data/GraphQL/Encoder.hs
index 86f090b..a418893 100644
--- a/Data/GraphQL/Encoder.hs
+++ b/Data/GraphQL/Encoder.hs
@@ -1,12 +1,7 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 -- | This module defines a printer for the @GraphQL@ language.
 module Data.GraphQL.Encoder where
 
-#if !MIN_VERSION_base(4,8,0)
-import Control.Applicative ((<$>))
-import Data.Monoid (Monoid, mconcat, mempty)
-#endif
 import Data.Monoid ((<>))
 
 import Data.Text (Text, cons, intercalate, pack, snoc)
diff --git a/Data/GraphQL/Error.hs b/Data/GraphQL/Error.hs
index 74f08e4..8c24a81 100644
--- a/Data/GraphQL/Error.hs
+++ b/Data/GraphQL/Error.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 module Data.GraphQL.Error (
   parseError,
@@ -15,12 +14,6 @@ import Data.Text (Text, pack)
 
 import Control.Arrow ((&&&))
 
-#if !MIN_VERSION_base(4,8,0)
-import Control.Applicative (Applicative, pure)
-import Data.Foldable (Foldable, concatMap)
-import Prelude hiding (concatMap)
-#endif
-
 -- | Wraps a parse error into a list of errors.
 parseError :: Applicative f => String -> f Aeson.Value
 parseError s =
diff --git a/Data/GraphQL/Execute.hs b/Data/GraphQL/Execute.hs
index 86887ff..a7e3c91 100644
--- a/Data/GraphQL/Execute.hs
+++ b/Data/GraphQL/Execute.hs
@@ -1,11 +1,7 @@
-{-# LANGUAGE CPP #-}
 -- | This module provides the function to execute a @GraphQL@ request --
 --   according to a 'Schema'.
 module Data.GraphQL.Execute (execute) where
 
-#if !MIN_VERSION_base(4,8,0)
-import Control.Applicative ((<$>))
-#endif
 import Control.Applicative (Alternative)
 import Data.Maybe (catMaybes)
 
diff --git a/Data/GraphQL/Parser.hs b/Data/GraphQL/Parser.hs
index 227c9a8..2de09b0 100644
--- a/Data/GraphQL/Parser.hs
+++ b/Data/GraphQL/Parser.hs
@@ -1,14 +1,9 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 -- | This module defines a parser for @GraphQL@ request documents.
 module Data.GraphQL.Parser where
 
 import Prelude hiding (takeWhile)
 
-#if !MIN_VERSION_base(4,8,0)
-import Control.Applicative ((<$>), (<*>), (*>), (<*), (<$), pure)
-import Data.Monoid (Monoid, mempty)
-#endif
 import Control.Applicative ((<|>), empty, many, optional)
 import Control.Monad (when)
 import Data.Char (isDigit, isSpace)
diff --git a/Data/GraphQL/Schema.hs b/Data/GraphQL/Schema.hs
index 7966392..b8668d9 100644
--- a/Data/GraphQL/Schema.hs
+++ b/Data/GraphQL/Schema.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE LambdaCase #-}
 -- | This module provides a representation of a @GraphQL@ Schema in addition to
@@ -23,16 +22,8 @@ module Data.GraphQL.Schema
   , Value(..)
   ) where
 
-#if !MIN_VERSION_base(4,8,0)
-import Control.Applicative (pure)
-import Control.Arrow (first)
-import Data.Foldable (foldMap)
-import Data.Traversable (traverse)
-import Data.Monoid (Monoid(mempty,mappend))
-#else
 import Data.Bifunctor (first)
 import Data.Monoid (Alt(Alt,getAlt))
-#endif
 import Control.Applicative (Alternative((<|>), empty))
 import Data.Maybe (catMaybes)
 import Data.Foldable (fold)
@@ -142,11 +133,3 @@ field _ = Nothing
 -- | Returns a list of the 'Field's contained in the given 'SelectionSet'.
 fields :: SelectionSet -> [Field]
 fields = catMaybes . fmap field
-
-#if !MIN_VERSION_base(4,8,0)
-newtype Alt f a = Alt {getAlt :: f a}
-
-instance Alternative f => Monoid (Alt f a) where
-        mempty = Alt empty
-        Alt x `mappend` Alt y = Alt $ x <|> y
-#endif
diff --git a/graphql.cabal b/graphql.cabal
index 86eec78..b73e259 100644
--- a/graphql.cabal
+++ b/graphql.cabal
@@ -14,7 +14,7 @@ copyright:           Copyright (C) 2015-2016 J. Daniel Navarro
 category:            Web
 build-type:          Simple
 cabal-version:       >=1.10
-tested-with:         GHC == 7.8.4, GHC == 7.10.3
+tested-with:         GHC == 7.10.3, GHC==8.0.1
 extra-source-files:  README.md CHANGELOG.md stack.yaml
                      docs/tutorial/tutorial.lhs
 data-files:          tests/data/*.graphql
@@ -35,6 +35,11 @@ library
                        base >= 4.7 && < 5,
                        text >= 0.11.3.1,
                        unordered-containers >= 0.2.5.0
+  if impl(ghc >= 8.0)
+    ghc-options: -Wcompat -Wnoncanonical-monad-instances -Wnoncanonical-monadfail-instances
+  else
+    -- provide/emulate `Control.Monad.Fail` and `Data.Semigroups` API for pre-GHC8
+    build-depends: fail == 4.9.*, semigroups == 0.18.*
 
 test-suite tasty
   default-language:    Haskell2010