diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+0.1.1.0 (May 8, 2020)
+
+* Support GHC 8.10.1
+
 0.1.0.1 (April 1, 2020)
 
 * Don't fail if 'git' or 'hg' commands cannot be found.
diff --git a/Retrie/ExactPrint.hs b/Retrie/ExactPrint.hs
--- a/Retrie/ExactPrint.hs
+++ b/Retrie/ExactPrint.hs
@@ -121,22 +121,22 @@
 fixOneExpr _ e = return e
 
 fixOnePat :: Monad m => FixityEnv -> LPat GhcPs -> TransformT m (LPat GhcPs)
-#if __GLASGOW_HASKELL__ < 808
-fixOnePat env (L l2 (ConPatIn op2 (InfixCon ap1@(L l1 (ConPatIn op1 (InfixCon x y))) z)))
+#if __GLASGOW_HASKELL__ == 808
+fixOnePat env (dL -> L l2 (ConPatIn op2 (InfixCon (dL -> ap1@(L l1 (ConPatIn op1 (InfixCon x y)))) z)))
   | associatesRight (lookupOpRdrName op1 env) (lookupOpRdrName op2 env) = do
     let ap2' = L l2 (ConPatIn op2 (InfixCon y z))
     swapEntryDPT ap1 ap2'
     transferAnnsT isComma ap2' ap1
-    rhs <- fixOnePat env ap2'
-    return $ L l1 (ConPatIn op1 (InfixCon x rhs))
+    rhs <- fixOnePat env (composeSrcSpan ap2')
+    return $ cL l1 (ConPatIn op1 (InfixCon x rhs))
 #else
-fixOnePat env (dL -> L l2 (ConPatIn op2 (InfixCon (dL -> ap1@(L l1 (ConPatIn op1 (InfixCon x y)))) z)))
+fixOnePat env (L l2 (ConPatIn op2 (InfixCon ap1@(L l1 (ConPatIn op1 (InfixCon x y))) z)))
   | associatesRight (lookupOpRdrName op1 env) (lookupOpRdrName op2 env) = do
     let ap2' = L l2 (ConPatIn op2 (InfixCon y z))
     swapEntryDPT ap1 ap2'
     transferAnnsT isComma ap2' ap1
-    rhs <- fixOnePat env (composeSrcSpan ap2')
-    return $ cL l1 (ConPatIn op1 (InfixCon x rhs))
+    rhs <- fixOnePat env ap2'
+    return $ L l1 (ConPatIn op1 (InfixCon x rhs))
 #endif
 fixOnePat _ e = return e
 
@@ -173,11 +173,11 @@
 fixOneEntryExpr e = return e
 
 fixOneEntryPat :: Monad m => LPat GhcPs -> TransformT m (LPat GhcPs)
-#if __GLASGOW_HASKELL__ < 808
-fixOneEntryPat p@(L _ (ConPatIn _ (InfixCon x _))) = fixOneEntry p x
-#else
+#if __GLASGOW_HASKELL__ == 808
 fixOneEntryPat p@(ConPatIn _ (InfixCon x _)) =
   composeSrcSpan <$> fixOneEntry (dL p) (dL x)
+#else
+fixOneEntryPat p@(L _ (ConPatIn _ (InfixCon x _))) = fixOneEntry p x
 #endif
 fixOneEntryPat p = return p
 
@@ -206,7 +206,13 @@
 parseContentNoFixity fp str = do
   r <- Parsers.parseModuleFromString fp str
   case r of
-    Left msg -> fail $ show msg
+    Left msg -> do
+#if __GLASGOW_HASKELL__ < 810
+      fail $ show msg
+#else
+      join $ Parsers.withDynFlags $ \dflags -> printBagOfErrors dflags msg
+      fail "parse failed"
+#endif
     Right (anns, m) -> return $ unsafeMkA m anns 0
 
 parseContent :: FixityEnv -> FilePath -> String -> IO AnnotatedModule
@@ -250,13 +256,16 @@
 parseType = parseHelper "parseType" Parsers.parseType
 
 parseHelper :: FilePath -> Parsers.Parser a -> String -> IO (Annotated a)
-parseHelper fp parser str = do
-  r <- Parsers.withDynFlags p
-  case r of
+parseHelper fp parser str = join $ Parsers.withDynFlags $ \dflags ->
+  case parser dflags fp str of
+#if __GLASGOW_HASKELL__ < 810
     Left (_, msg) -> throwIO $ ErrorCall msg
+#else
+    Left errBag -> do
+      printBagOfErrors dflags errBag
+      throwIO $ ErrorCall "parse failed"
+#endif
     Right (anns, x) -> return $ unsafeMkA x anns 0
-  where
-    p dflags = parser dflags fp str
 
 -------------------------------------------------------------------------------
 
diff --git a/Retrie/Expr.hs b/Retrie/Expr.hs
--- a/Retrie/Expr.hs
+++ b/Retrie/Expr.hs
@@ -52,7 +52,7 @@
 #if __GLASGOW_HASKELL__ < 806
   lv@(L _ v') <- cloneT (noLoc (HsVar r))
 #else
-  lv@(L _ v') <- cloneT (noLoc (HsVar noExt r))
+  lv@(L _ v') <- cloneT (noLoc (HsVar noExtField r))
 #endif
   case v' of
 #if __GLASGOW_HASKELL__ < 806
@@ -92,7 +92,7 @@
 #if __GLASGOW_HASKELL__ < 806
       mkMatchGroup Generated [mkMatch LambdaExpr vs e (noLoc EmptyLocalBinds)]
 #else
-      mkMatchGroup Generated [mkMatch LambdaExpr vs e (noLoc (EmptyLocalBinds noExt))]
+      mkMatchGroup Generated [mkMatch LambdaExpr vs e (noLoc (EmptyLocalBinds noExtField))]
 #endif
   m' <- case unLoc $ mg_alts mg of
     [m] -> setAnnsFor m [(G AnnLam, DP (0,0)),(G AnnRarrow, DP (0,1))]
@@ -100,7 +100,7 @@
 #if __GLASGOW_HASKELL__ < 806
   cloneT $ noLoc $ HsLam mg { mg_alts = noLoc [m'] }
 #else
-  cloneT $ noLoc $ HsLam noExt mg { mg_alts = noLoc [m'] }
+  cloneT $ noLoc $ HsLam noExtField mg { mg_alts = noLoc [m'] }
 #endif
 
 mkLet :: Monad m => HsLocalBinds GhcPs -> LHsExpr GhcPs -> TransformT m (LHsExpr GhcPs)
@@ -110,7 +110,7 @@
 #if __GLASGOW_HASKELL__ < 806
   le <- mkLoc $ HsLet llbs e
 #else
-  le <- mkLoc $ HsLet noExt llbs e
+  le <- mkLoc $ HsLet noExtField llbs e
 #endif
   setAnnsFor le [(G AnnLet, DP (0,0)), (G AnnIn, DP (1,1))]
 
@@ -120,7 +120,7 @@
 #if __GLASGOW_HASKELL__ < 806
   f' <- mkLoc (HsApp f a)
 #else
-  f' <- mkLoc (HsApp noExt f a)
+  f' <- mkLoc (HsApp noExtField f a)
 #endif
   mkApps f' as
 
@@ -133,7 +133,7 @@
   mkLoc (HsAppsTy ts')
 #else
 mkHsAppsTy [] = error "mkHsAppsTy: empty list"
-mkHsAppsTy (t:ts) = foldM (\t1 t2 -> mkLoc (HsAppTy noExt t1 t2)) t ts
+mkHsAppsTy (t:ts) = foldM (\t1 t2 -> mkLoc (HsAppTy noExtField t1 t2)) t ts
 #endif
 
 mkTyVar :: Monad m => Located RdrName -> TransformT m (LHsType GhcPs)
@@ -141,7 +141,7 @@
 #if __GLASGOW_HASKELL__ < 806
   tv <- mkLoc (HsTyVar NotPromoted nm)
 #else
-  tv <- mkLoc (HsTyVar noExt NotPromoted nm)
+  tv <- mkLoc (HsTyVar noExtField NotPromoted nm)
 #endif
   _ <- setAnnsFor nm [(G AnnVal, DP (0,0))]
   swapEntryDPT tv nm
@@ -228,9 +228,9 @@
     go (ListPat _ ps) = do
       ps' <- mapM patToExpr ps
       lift $ do
-        el <- mkLoc $ ExplicitList noExt Nothing ps'
+        el <- mkLoc $ ExplicitList noExtField Nothing ps'
         setAnnsFor el [(G AnnOpenS, DP (0,0)), (G AnnCloseS, DP (0,0))]
-    go (ParPat _ p') = lift . mkParen (HsPar noExt) =<< patToExpr p'
+    go (ParPat _ p') = lift . mkParen (HsPar noExtField) =<< patToExpr p'
     go (VarPat _ i) = lift $ mkLocatedHsVar i
     go SigPat{} = error "patToExpr SigPat"
     go XPat{} = error "patToExpr XPat"
@@ -249,7 +249,7 @@
                          <*> pure PlaceHolder
                          <*> patToExpr y
 #else
-  lift . mkLoc =<< OpApp <$> pure noExt
+  lift . mkLoc =<< OpApp <$> pure noExtField
                          <*> patToExpr x
                          <*> lift (mkLocatedHsVar con)
                          <*> patToExpr y
@@ -290,7 +290,7 @@
 #if __GLASGOW_HASKELL__ < 806
     mkParen HsPar le
 #else
-    mkParen (HsPar noExt) le
+    mkParen (HsPar noExtField) le
 #endif
   | otherwise = return le
   where
@@ -334,7 +334,7 @@
 #if __GLASGOW_HASKELL__ < 806
   | needed ty = mkParen HsParTy lty
 #else
-  | needed ty = mkParen (HsParTy noExt) lty
+  | needed ty = mkParen (HsParTy noExtField) lty
 #endif
   | otherwise = return lty
   where
diff --git a/Retrie/GHC.hs b/Retrie/GHC.hs
--- a/Retrie/GHC.hs
+++ b/Retrie/GHC.hs
@@ -12,8 +12,14 @@
   , module BasicTypes
   , module FastString
   , module FastStringEnv
+#if __GLASGOW_HASKELL__ < 810
   , module HsExpr
   , module HsSyn
+#else
+  , module ErrUtils
+  , module GHC.Hs.Expr
+  , module GHC.Hs
+#endif
   , module Module
   , module Name
   , module OccName
@@ -29,12 +35,18 @@
 import BasicTypes
 import FastString
 import FastStringEnv
+#if __GLASGOW_HASKELL__ < 810
 import HsExpr
 #if __GLASGOW_HASKELL__ < 806
 import HsSyn hiding (HasDefault(..))
 #else
 import HsSyn
 #endif
+#else
+import ErrUtils
+import GHC.Hs.Expr
+import GHC.Hs
+#endif
 import Module
 import Name
 import OccName
@@ -130,3 +142,9 @@
   , riLHS :: LHsExpr GhcPs
   , riRHS :: LHsExpr GhcPs
   }
+
+#if __GLASGOW_HASKELL__ < 806
+#elif __GLASGOW_HASKELL__ < 810
+noExtField :: NoExt
+noExtField = noExt
+#endif
diff --git a/Retrie/PatternMap/Instances.hs b/Retrie/PatternMap/Instances.hs
--- a/Retrie/PatternMap/Instances.hs
+++ b/Retrie/PatternMap/Instances.hs
@@ -356,7 +356,7 @@
 #if __GLASGOW_HASKELL__ < 806
           go (HsApp l (noLoc (HsPar r)))
 #else
-          go (HsApp noExt l (noLoc (HsPar noExt r)))
+          go (HsApp noExtField l (noLoc (HsPar noExtField r)))
 #endif
       dollarFork _ _ _ = m
 
@@ -457,15 +457,17 @@
       go HsSpliceE{} = missingSyntax "HsSpliceE"
       go HsProc{} = missingSyntax "HsProc"
       go HsStatic{} = missingSyntax "HsStatic"
+#if __GLASGOW_HASKELL__ < 810
       go HsArrApp{} = missingSyntax "HsArrApp"
       go HsArrForm{} = missingSyntax "HsArrForm"
-      go HsTick{} = missingSyntax "HsTick"
-      go HsBinTick{} = missingSyntax "HsBinTick"
-      go HsTickPragma{} = missingSyntax "HsTickPragma"
       go EWildPat{} = missingSyntax "EWildPat"
       go EAsPat{} = missingSyntax "EAsPat"
       go EViewPat{} = missingSyntax "EViewPat"
       go ELazyPat{} = missingSyntax "ELazyPat"
+#endif
+      go HsTick{} = missingSyntax "HsTick"
+      go HsBinTick{} = missingSyntax "HsBinTick"
+      go HsTickPragma{} = missingSyntax "HsTickPragma"
       go HsWrap{} = missingSyntax "HsWrap"
       go HsUnboundVar{} = missingSyntax "HsUnboundVar"
       go HsRecFld{} = missingSyntax "HsRecFld"
@@ -710,7 +712,12 @@
 emptyCDMapWrapper = CDMap mEmpty mEmpty
 
 instance PatternMap CDMap where
+#if __GLASGOW_HASKELL__ < 810
   type Key CDMap = HsConDetails (LPat GhcPs) (HsRecFields GhcPs (LPat GhcPs))
+#else
+  -- We must manually expand 'LPat' to avoid UndecidableInstances in GHC 8.10+
+  type Key CDMap = HsConDetails (Located (Pat GhcPs)) (HsRecFields GhcPs (Located (Pat GhcPs)))
+#endif
 
   mEmpty :: CDMap a
   mEmpty = CDEmpty
@@ -763,7 +770,12 @@
 emptyPatMapWrapper = PatMap mEmpty mEmpty mEmpty mEmpty mEmpty mEmpty
 
 instance PatternMap PatMap where
+#if __GLASGOW_HASKELL__ < 810
   type Key PatMap = LPat GhcPs
+#else
+  -- We must manually expand 'LPat' to avoid UndecidableInstances in GHC 8.10+
+  type Key PatMap = Located (Pat GhcPs)
+#endif
 
   mEmpty :: PatMap a
   mEmpty = PatEmpty
@@ -1187,7 +1199,11 @@
 #if __GLASGOW_HASKELL__ < 806
        , tyHsAppsTy :: ListMap AppTyMap a
 #endif
+#if __GLASGOW_HASKELL__ < 810
        , tyHsForAllTy :: ForAllTyMap a -- See Note [Telescope]
+#else
+       , tyHsForAllTy :: ForallVisMap (ForAllTyMap a) -- See Note [Telescope]
+#endif
        , tyHsFunTy :: TyMap (TyMap a)
        , tyHsListTy :: TyMap a
        , tyHsParTy :: TyMap a
@@ -1271,7 +1287,12 @@
         m { tyHsTupleTy = mAlter env vs ts (toA (mAlter env vs tys f)) (tyHsTupleTy m) }
 #else
       go (HsAppTy _ ty1 ty2) = m { tyHsAppTy = mAlter env vs ty1 (toA (mAlter env vs ty2 f)) (tyHsAppTy m) }
+#if __GLASGOW_HASKELL__ < 810
       go (HsForAllTy _ bndrs ty') = m { tyHsForAllTy = mAlter env vs (bndrs, ty') f (tyHsForAllTy m) }
+#else
+      go (HsForAllTy _ vis bndrs ty') =
+        m { tyHsForAllTy = mAlter env vs vis (toA (mAlter env vs (bndrs, ty') f)) (tyHsForAllTy m) }
+#endif
       go (HsFunTy _ ty1 ty2) = m { tyHsFunTy = mAlter env vs ty1 (toA (mAlter env vs ty2 f)) (tyHsFunTy m) }
       go (HsListTy _ ty') = m { tyHsListTy = mAlter env vs ty' f (tyHsListTy m) }
       go (HsParTy _ ty') = m { tyHsParTy = mAlter env vs ty' f (tyHsParTy m) }
@@ -1316,7 +1337,12 @@
       go (HsTyVar _ v) = mapFor tyHsTyVar >=> mMatch env (unLoc v)
 #else
       go (HsAppTy _ ty1 ty2) = mapFor tyHsAppTy >=> mMatch env ty1 >=> mMatch env ty2
+#if __GLASGOW_HASKELL__ < 810
       go (HsForAllTy _ bndrs ty') = mapFor tyHsForAllTy >=> mMatch env (bndrs, ty')
+#else
+      go (HsForAllTy _ vis bndrs ty') =
+        mapFor tyHsForAllTy >=> mMatch env vis >=> mMatch env (bndrs, ty')
+#endif
       go (HsFunTy _ ty1 ty2) = mapFor tyHsFunTy >=> mMatch env ty1 >=> mMatch env ty2
       go (HsListTy _ ty') = mapFor tyHsListTy >=> mMatch env ty'
       go (HsParTy _ ty') = mapFor tyHsParTy >=> mMatch env ty'
@@ -1474,7 +1500,6 @@
   mMatch env HsConstraintTuple = mapFor tsConstraint >=> mMatch env ()
   mMatch env HsBoxedOrConstraintTuple = mapFor tsBoxedOrConstraint >=> mMatch env ()
 
-
 ------------------------------------------------------------------------
 
 -- Note [Telescope]
@@ -1543,3 +1568,34 @@
 #endif
     let env' = extendMatchEnv env [v]
     in mapFor fatKinded >=> mMatch env k >=> mMatch env' (rest, ty)
+
+#if __GLASGOW_HASKELL__ < 810
+#else
+data ForallVisMap a = ForallVisMap
+  { favVis :: MaybeMap a
+  , favInvis :: MaybeMap a
+  }
+  deriving (Functor)
+
+instance PatternMap ForallVisMap where
+  type Key ForallVisMap = ForallVisFlag
+
+  mEmpty :: ForallVisMap a
+  mEmpty = ForallVisMap mEmpty mEmpty
+
+  mUnion :: ForallVisMap a -> ForallVisMap a -> ForallVisMap a
+  mUnion m1 m2 = ForallVisMap
+    { favVis = unionOn favVis m1 m2
+    , favInvis = unionOn favInvis m1 m2
+    }
+
+  mAlter :: AlphaEnv -> Quantifiers -> Key ForallVisMap -> A a -> ForallVisMap a -> ForallVisMap a
+  mAlter env vs ForallVis f m =
+    m { favVis = mAlter env vs () f (favVis m) }
+  mAlter env vs ForallInvis f m =
+    m { favInvis = mAlter env vs () f (favInvis m) }
+
+  mMatch :: MatchEnv -> Key ForallVisMap -> (Substitution, ForallVisMap a) -> [(Substitution, a)]
+  mMatch env ForallVis = mapFor favVis >=> mMatch env ()
+  mMatch env ForallInvis = mapFor favInvis >=> mMatch env ()
+#endif
diff --git a/Retrie/Rewrites/Function.hs b/Retrie/Rewrites/Function.hs
--- a/Retrie/Rewrites/Function.hs
+++ b/Retrie/Rewrites/Function.hs
@@ -123,13 +123,13 @@
     right op [r] = mkLoc (SectionR op r)
     right _ _ = fail "backtickRules - right: impossible!"
 #else
-    both op [l, r] = mkLoc (OpApp noExt l op r)
+    both op [l, r] = mkLoc (OpApp noExtField l op r)
     both _ _ = fail "backtickRules - both: impossible!"
 
-    left op [l] = mkLoc (SectionL noExt l op)
+    left op [l] = mkLoc (SectionL noExtField l op)
     left _ _ = fail "backtickRules - left: impossible!"
 
-    right op [r] = mkLoc (SectionR noExt op r)
+    right op [r] = mkLoc (SectionR noExtField op r)
     right _ _ = fail "backtickRules - right: impossible!"
 #endif
   qs <- makeFunctionQuery e imps dir grhss both (ps, [])
diff --git a/retrie.cabal b/retrie.cabal
--- a/retrie.cabal
+++ b/retrie.cabal
@@ -4,7 +4,7 @@
 -- LICENSE file in the root directory of this source tree.
 --
 name: retrie
-version: 0.1.0.1
+version: 0.1.1.0
 synopsis: A powerful, easy-to-use codemodding tool for Haskell.
 homepage: https://github.com/facebookincubator/retrie
 bug-reports: https://github.com/facebookincubator/retrie/issues
@@ -23,7 +23,7 @@
   README.md
   tests/inputs/*.custom
   tests/inputs/*.test
-tested-with: GHC ==8.8.2 || ==8.6.5 || ==8.4.4
+tested-with: GHC ==8.10.1 || ==8.8.2 || ==8.6.5 || ==8.4.4
 
 description:
   Retrie is a tool for codemodding Haskell. Key goals include:
@@ -75,13 +75,13 @@
   build-depends:
     ansi-terminal >= 0.10.3 && < 0.11,
     async >= 2.2.2 && < 2.3,
-    base >= 4.11 && < 4.14,
+    base >= 4.11 && < 4.15,
     bytestring >= 0.10.8 && < 0.11,
     containers >= 0.5.11 && < 0.7,
     data-default >= 0.7.1 && < 0.8,
     directory >= 1.3.1 && < 1.4,
     filepath >= 1.4.2 && < 1.5,
-    ghc >= 8.4 && < 8.10,
+    ghc >= 8.4 && < 8.12,
     ghc-exactprint >= 0.6.2 && < 0.7,
     haskell-src-exts >= 1.23.0 && < 1.24,
     mtl >= 2.2.2 && < 2.3,
@@ -102,7 +102,7 @@
   GHC-Options: -Wall
   build-depends:
     retrie,
-    base >= 4.11 && < 4.14,
+    base >= 4.11 && < 4.15,
     data-default
   default-language: Haskell2010
 
@@ -114,7 +114,7 @@
   GHC-Options: -Wall
   build-depends:
     retrie,
-    base >= 4.11 && < 4.14
+    base >= 4.11 && < 4.15
   default-language: Haskell2010
 
 test-suite test
@@ -139,13 +139,13 @@
   build-depends:
     retrie,
     HUnit,
-    base >= 4.11 && < 4.14,
+    base >= 4.11 && < 4.15,
     containers,
     data-default,
     deepseq,
     directory,
     filepath,
-    ghc >= 8.4 && < 8.10,
+    ghc >= 8.4 && < 8.12,
     ghc-paths,
     mtl,
     optparse-applicative,