diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,8 @@
 # Changelog for the [`ghc-typelits-knownnat`](http://hackage.haskell.org/package/ghc-typelits-knownnat) package
 
+## 0.4.1 *March 17th, 2018*
+* Add support for GHC 8.4.1
+
 ## 0.4 *January 4th, 2018*
 * Add partial GHC 8.4.1-alpha1 support
 * Drop `singletons` dependency [#15](https://github.com/clash-lang/ghc-typelits-knownnat/issues/15)
diff --git a/ghc-typelits-knownnat.cabal b/ghc-typelits-knownnat.cabal
--- a/ghc-typelits-knownnat.cabal
+++ b/ghc-typelits-knownnat.cabal
@@ -1,5 +1,5 @@
 name:                ghc-typelits-knownnat
-version:             0.4
+version:             0.4.1
 synopsis:            Derive KnownNat constraints from other KnownNat constraints
 description:
   A type checker plugin for GHC that can derive \"complex\" @KnownNat@
@@ -86,10 +86,10 @@
                        ViewPatterns
   build-depends:       base                      >= 4.9      && <5,
                        ghc                       >= 8.0.1    && <8.6,
-                       ghc-tcplugins-extra       >= 0.2,
+                       ghc-tcplugins-extra       >= 0.2.4,
                        ghc-typelits-natnormalise >= 0.5.2    && <0.6,
                        transformers              >= 0.5.2.0  && <0.6,
-                       template-haskell          >= 2.11.0.0 && <2.13
+                       template-haskell          >= 2.11.0.0 && <2.14
   hs-source-dirs:      src
   default-language:    Haskell2010
   if flag(deverror)
@@ -103,7 +103,7 @@
   Other-Modules:       TestFunctions
   build-depends:       base                      >= 4.8   && <5,
                        ghc-typelits-knownnat,
-                       ghc-typelits-natnormalise >= 0.5   && <0.6,
+                       ghc-typelits-natnormalise >= 0.5.9 && <0.6,
                        tasty                     >= 0.10,
                        tasty-hunit               >= 0.9,
                        tasty-quickcheck          >= 0.8
diff --git a/src/GHC/TypeLits/KnownNat/Solver.hs b/src/GHC/TypeLits/KnownNat/Solver.hs
--- a/src/GHC/TypeLits/KnownNat/Solver.hs
+++ b/src/GHC/TypeLits/KnownNat/Solver.hs
@@ -84,6 +84,7 @@
 
 -}
 
+{-# LANGUAGE CPP           #-}
 {-# LANGUAGE LambdaCase    #-}
 {-# LANGUAGE TupleSections #-}
 {-# LANGUAGE ViewPatterns  #-}
@@ -100,6 +101,9 @@
 import Data.Maybe                   (catMaybes,mapMaybe)
 import GHC.TcPluginM.Extra          (lookupModule, lookupName, newWanted,
                                      tracePlugin)
+#if MIN_VERSION_ghc(8,4,0)
+import GHC.TcPluginM.Extra          (flattenGivens, mkSubst', substType)
+#endif
 import GHC.TypeLits.Normalise.SOP   (SOP (..), Product (..), Symbol (..))
 import GHC.TypeLits.Normalise.Unify (CType (..),normaliseNat,reifySOP)
 
@@ -115,7 +119,10 @@
 import Plugins    (Plugin (..), defaultPlugin)
 import PrelNames  (knownNatClassName)
 import TcEvidence (EvTerm (..), EvLit (EvNum), mkEvCast, mkTcSymCo, mkTcTransCo)
-import TcPluginM  (TcPluginM, tcLookupClass, getInstEnvs, zonkCt)
+#if !MIN_VERSION_ghc(8,4,0)
+import TcPluginM  (zonkCt)
+#endif
+import TcPluginM  (TcPluginM, tcLookupClass, getInstEnvs)
 import TcRnTypes  (Ct, TcPlugin(..), TcPluginResult (..), ctEvidence, ctEvLoc,
                    ctEvPred, ctEvTerm, ctLoc, ctLocSpan, isWanted,
                    mkNonCanonical, setCtLoc, setCtLocSpan)
@@ -235,12 +242,22 @@
 solveKnownNat defs  givens  _deriveds wanteds = do
   -- GHC 7.10 puts deriveds with the wanteds, so filter them out
   let wanteds'   = filter (isWanted . ctEvidence) wanteds
+#if MIN_VERSION_ghc(8,4,0)
+      subst      = mkSubst' givens
+      kn_wanteds = map (\(x,y,z) -> (x,y,substType subst z))
+                 $ mapMaybe toKnConstraint wanteds'
+#else
       kn_wanteds = mapMaybe toKnConstraint wanteds'
+#endif
   case kn_wanteds of
     [] -> return (TcPluginOk [] [])
     _  -> do
       -- Make a lookup table for all the [G]iven constraints
+#if MIN_VERSION_ghc(8,4,0)
+      let given_map = map toGivenEntry (givens ++ flattenGivens givens)
+#else
       given_map <- mapM (fmap toGivenEntry . zonkCt) givens
+#endif
       -- Try to solve the wanted KnownNat constraints given the [G]iven
       -- KnownNat constraints
       (solved,new) <- (unzip . catMaybes) <$> (mapM (constraintToEvTerm defs given_map) kn_wanteds)