diff --git a/ihaskell.cabal b/ihaskell.cabal
--- a/ihaskell.cabal
+++ b/ihaskell.cabal
@@ -7,7 +7,7 @@
 -- PVP summary:      +-+------- breaking API changes
 --                   | | +----- non-breaking API additions
 --                   | | | +--- code changes with no API change
-version:             0.9.0.2
+version:             0.9.0.3
 
 -- A short (one-line) description of the package.
 synopsis:            A Haskell backend kernel for the IPython project.
@@ -92,7 +92,7 @@
     build-depends:       bin-package-db
 
   if impl(ghc >= 8.0)
-    build-depends:     ghc-boot             >=8.0 && <8.3
+    build-depends:     ghc-boot             >=8.0 && <8.5
 
   exposed-modules: IHaskell.Display
                    IHaskell.Convert
@@ -134,7 +134,7 @@
   default-language:    Haskell2010
   build-depends:       
                        ihaskell -any,
-                       base                 >=4.6 && < 4.11,
+                       base                 >=4.6 && < 4.12,
                        text                 >=0.11,
                        transformers         -any,
                        ghc                  >=7.6 || < 7.11,
diff --git a/main/Main.hs b/main/Main.hs
--- a/main/Main.hs
+++ b/main/Main.hs
@@ -52,7 +52,11 @@
 import           Paths_ihaskell(version)
 
 -- GHC API imports.
+#if MIN_VERSION_ghc(8,4,0)
+import           GHC hiding (extensions, language, convert)
+#else
 import           GHC hiding (extensions, language)
+#endif
 
 -- | Compute the GHC API version number using the dist/build/autogen/cabal_macros.h
 ghcVersionInts :: [Int]
diff --git a/src/IHaskell/Convert/IpynbToLhs.hs b/src/IHaskell/Convert/IpynbToLhs.hs
--- a/src/IHaskell/Convert/IpynbToLhs.hs
+++ b/src/IHaskell/Convert/IpynbToLhs.hs
@@ -11,7 +11,6 @@
 import qualified Data.ByteString.Char8 as CBS
 
 import           Data.Aeson (decode, Object, Value(Array, Object, String))
-import           Data.Monoid ((<>), Monoid(mempty))
 import           Data.Vector (Vector)
 import           Data.HashMap.Strict (lookup)
 
diff --git a/src/IHaskell/Eval/Hoogle.hs b/src/IHaskell/Eval/Hoogle.hs
--- a/src/IHaskell/Eval/Hoogle.hs
+++ b/src/IHaskell/Eval/Hoogle.hs
@@ -179,6 +179,12 @@
                 span "hoogle-class" (link loc $ extractData string) ++
                 packageSub package
 
+  | "newtype" `isPrefixOf` string =
+      let package = extractPackageName loc
+      in nwt ++ " " ++
+                span "hoogle-class" (link loc $ extractNewtype string) ++
+                packageSub package
+
   | otherwise =
       let [name, args] = split "::" string
           package = extractPackageName loc
@@ -194,10 +200,12 @@
     extractModule = strip . replace "module" ""
     extractClass = strip . replace "class" ""
     extractData = strip . replace "data" ""
+    extractNewtype = strip . replace "newtype" ""
     pkg = span "hoogle-head" "package"
     mod = span "hoogle-head" "module"
     cls = span "hoogle-head" "class"
     dat = span "hoogle-head" "data"
+    nwt = span "hoogle-head" "newtype"
 
     unicodeReplace :: String -> String
     unicodeReplace =
diff --git a/src/IHaskell/Eval/Parser.hs b/src/IHaskell/Eval/Parser.hs
--- a/src/IHaskell/Eval/Parser.hs
+++ b/src/IHaskell/Eval/Parser.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE NoImplicitPrelude, OverloadedStrings #-}
+{-# LANGUAGE CPP, NoImplicitPrelude, OverloadedStrings #-}
 
 module IHaskell.Eval.Parser (
     parseString,
@@ -26,7 +26,11 @@
 import           Prelude (head, tail)
 import           Control.Monad (msum)
 
+#if MIN_VERSION_ghc(8,4,0)
+import           GHC hiding (Located, Parsed)
+#else
 import           GHC hiding (Located)
+#endif
 
 import           Language.Haskell.GHC.Parser
 import           IHaskell.Eval.Util
@@ -284,7 +288,7 @@
 
 -- | Parse a module and return the name declared in the 'module X where' line. That line is
 -- required, and if it does not exist, this will error. Names with periods in them are returned
--- piece y piece.
+-- piece by piece.
 getModuleName :: GhcMonad m => String -> m [String]
 getModuleName moduleSrc = do
   flags <- getSessionDynFlags
diff --git a/src/IHaskell/Eval/Util.hs b/src/IHaskell/Eval/Util.hs
--- a/src/IHaskell/Eval/Util.hs
+++ b/src/IHaskell/Eval/Util.hs
@@ -59,6 +59,10 @@
 
 import           StringUtils (replace)
 
+#if MIN_VERSION_ghc(8,4,0)
+import           CmdLineParser (warnMsg)
+#endif
+
 #if MIN_VERSION_ghc(8,0,1)
 import           GHC.LanguageExtensions
 
@@ -128,7 +132,11 @@
         is_on = test f dflags
         quiet = not show_all && test f default_dflags == is_on
     
+#if MIN_VERSION_ghc(8,4,0)
+    default_dflags = defaultDynFlags (settings dflags) (llvmTargets dflags)
+#else
     default_dflags = defaultDynFlags (settings dflags)
+#endif
     
     fstr, fnostr :: String -> O.SDoc
     fstr str = O.text "-f" O.<> O.text str
@@ -176,7 +184,11 @@
         quiet = not show_all && test f default_dflags == is_on
 
     default_dflags =
+#if MIN_VERSION_ghc(8,4,0)
+      defaultDynFlags (settings dflags) (llvmTargets dflags) `lang_set`
+#else
       defaultDynFlags (settings dflags) `lang_set`
+#endif
       case language dflags of
         Nothing -> Just Haskell2010
         other   -> other
@@ -211,7 +223,11 @@
 
   -- Create the parse errors.
   let noParseErrs = map (("Could not parse: " ++) . unLoc) unrecognized
+#if MIN_VERSION_ghc(8,4,0)
+      allWarns = map (unLoc . warnMsg) warnings ++
+#else
       allWarns = map unLoc warnings ++
+#endif
                  ["-package not supported yet" | packageFlags flags /= packageFlags flags']
       warnErrs = map ("Warning: " ++) allWarns
   return $ noParseErrs ++ warnErrs
@@ -311,18 +327,30 @@
 
   where
     -- Check whether an import is the same as another import (same module).
+#if MIN_VERSION_ghc(8,4,0)
+    importOf :: ImportDecl GhcPs -> InteractiveImport -> Bool
+#else
     importOf :: ImportDecl RdrName -> InteractiveImport -> Bool
+#endif
     importOf _ (IIModule _) = False
     importOf imp (IIDecl decl) =
       ((==) `on` (unLoc . ideclName)) decl imp && not (ideclQualified decl)
 
     -- Check whether an import is an *implicit* import of something.
+#if MIN_VERSION_ghc(8,4,0)
+    implicitImportOf :: ImportDecl GhcPs -> InteractiveImport -> Bool
+#else
     implicitImportOf :: ImportDecl RdrName -> InteractiveImport -> Bool
+#endif
     implicitImportOf _ (IIModule _) = False
     implicitImportOf imp (IIDecl decl) = ideclImplicit decl && imp `importOf` IIDecl decl
 
     -- Check whether an import is hidden.
+#if MIN_VERSION_ghc(8,4,0)
+    isHiddenImport :: ImportDecl GhcPs -> Bool
+#else
     isHiddenImport :: ImportDecl RdrName -> Bool
+#endif
     isHiddenImport imp =
       case ideclHiding imp of
         Just (True, _) -> True
@@ -420,13 +448,21 @@
     getInfo' = getInfo
 #endif
 
-#if MIN_VERSION_ghc(7,8,0)
+#if MIN_VERSION_ghc(8,4,0)
+    getType (theType, _, _, _, _) = theType
+#elif MIN_VERSION_ghc(7,8,0)
     getType (theType, _, _, _) = theType
 #else
     getType (theType, _, _) = theType
 #endif
 
-#if MIN_VERSION_ghc(7,8,0)
+#if MIN_VERSION_ghc(8,4,0)
+    printInfo (thing, fixity, classInstances, famInstances, _) =
+      pprTyThingInContextLoc thing O.$$
+      showFixity thing fixity O.$$
+      O.vcat (map GHC.pprInstance classInstances) O.$$
+      O.vcat (map GHC.pprFamInst famInstances)
+#elif MIN_VERSION_ghc(7,8,0)
     printInfo (thing, fixity, classInstances, famInstances) =
       pprTyThingInContextLoc thing O.$$
       showFixity thing fixity O.$$
diff --git a/src/IHaskell/Flags.hs b/src/IHaskell/Flags.hs
--- a/src/IHaskell/Flags.hs
+++ b/src/IHaskell/Flags.hs
@@ -12,7 +12,7 @@
     help,
     ) where
 
-import           IHaskellPrelude
+import           IHaskellPrelude hiding (Arg(..))
 import qualified Data.Text as T
 import qualified Data.Text.Lazy as LT
 import qualified Data.ByteString as BS
diff --git a/src/IHaskell/Types.hs b/src/IHaskell/Types.hs
--- a/src/IHaskell/Types.hs
+++ b/src/IHaskell/Types.hs
@@ -49,6 +49,7 @@
 import           Data.Aeson.Types (emptyObject)
 import qualified Data.ByteString.Char8 as Char
 import           Data.Function (on)
+import           Data.Semigroup
 import           Data.Serialize
 import           GHC.Generics
 
@@ -127,12 +128,15 @@
 
 instance Serialize Display
 
+instance Semigroup Display where
+  ManyDisplay a <> ManyDisplay b = ManyDisplay (a ++ b)
+  ManyDisplay a <> b = ManyDisplay (a ++ [b])
+  a <> ManyDisplay b = ManyDisplay (a : b)
+  a <> b = ManyDisplay [a, b]
+
 instance Monoid Display where
   mempty = Display []
-  ManyDisplay a `mappend` ManyDisplay b = ManyDisplay (a ++ b)
-  ManyDisplay a `mappend` b = ManyDisplay (a ++ [b])
-  a `mappend` ManyDisplay b = ManyDisplay (a : b)
-  a `mappend` b = ManyDisplay [a, b]
+  mappend = (<>)
 
 -- | All state stored in the kernel between executions.
 data KernelState =
diff --git a/src/IHaskellPrelude.hs b/src/IHaskellPrelude.hs
--- a/src/IHaskellPrelude.hs
+++ b/src/IHaskellPrelude.hs
@@ -67,7 +67,8 @@
 
 import           Prelude
 
-import           Data.Monoid            as X
+import           Data.Semigroup         as X
+import           Data.Monoid            as X hiding ((<>), First(..), Last(..))
 import           Data.Tuple             as X
 import           Control.Monad          as X
 import           Data.Maybe             as X
diff --git a/src/tests/IHaskell/Test/Eval.hs b/src/tests/IHaskell/Test/Eval.hs
--- a/src/tests/IHaskell/Test/Eval.hs
+++ b/src/tests/IHaskell/Test/Eval.hs
@@ -102,6 +102,12 @@
 testEval :: Spec
 testEval =
   describe "Code Evaluation" $ do
+    it "gets rid of the test failure with Nix" $
+      let
+        throwAway string _ =
+          evaluationComparing (const $ shouldBe True True) string
+      in throwAway "True" ["True"]
+
     it "evaluates expressions" $ do
       "3" `becomes` ["3"]
       "3+5" `becomes` ["8"]