diff --git a/cabal.project b/cabal.project
index c063a3fc3e..5ad04de72b 100644
--- a/cabal.project
+++ b/cabal.project
@@ -2,6 +2,11 @@ packages:
          ./
          ghcide
 
+source-repository-package
+  type: git
+  location: https://github.com/bubba/brittany.git
+  tag: c59655f10d5ad295c2481537fc8abf0a297d9d1c
+
 tests: true
 
 package *
@@ -14,4 +19,6 @@ package ghcide
 
 write-ghc-environment-files: never
 
-index-state: 2020-07-27T12:40:45Z
+index-state: 2020-08-07T11:45:57Z
+
+allow-newer: data-tree-print:base
diff --git a/exe/Main.hs b/exe/Main.hs
index a13d4d875f..725a752b95 100644
--- a/exe/Main.hs
+++ b/exe/Main.hs
@@ -67,10 +67,11 @@ import Ide.Plugin.Example                 as Example
 import Ide.Plugin.Example2                as Example2
 import Ide.Plugin.GhcIde                  as GhcIde
 import Ide.Plugin.Floskell                as Floskell
+import Ide.Plugin.Fourmolu                as Fourmolu
 import Ide.Plugin.Ormolu                  as Ormolu
 import Ide.Plugin.StylishHaskell          as StylishHaskell
 import Ide.Plugin.Retrie                  as Retrie
-#if AGPL && !MIN_VERSION_ghc(8,10,1)
+#if AGPL
 import Ide.Plugin.Brittany                as Brittany
 #endif
 import Ide.Plugin.Pragmas                 as Pragmas
@@ -102,15 +103,14 @@ idePlugins includeExamples = pluginDescToIdePlugins allPlugins
       GhcIde.descriptor  "ghcide"
       , Pragmas.descriptor  "pragmas"
       , Floskell.descriptor "floskell"
+      , Fourmolu.descriptor "fourmolu"
       -- , genericDescriptor     "generic"
       -- , ghcmodDescriptor      "ghcmod"
       , Ormolu.descriptor   "ormolu"
       , StylishHaskell.descriptor "stylish-haskell"
       , Retrie.descriptor "retrie"
 #if AGPL
-#if !MIN_VERSION_ghc(8,10,1)
       , Brittany.descriptor    "brittany"
-#endif
 #endif
       , Eval.descriptor "eval"
       ]
diff --git a/haskell-language-server.cabal b/haskell-language-server.cabal
index 3543db1c7e..488b6b684b 100644
--- a/haskell-language-server.cabal
+++ b/haskell-language-server.cabal
@@ -45,6 +45,7 @@ library
       Ide.Plugin.Eval
       Ide.Plugin.Example
       Ide.Plugin.Example2
+      Ide.Plugin.Fourmolu
       Ide.Plugin.GhcIde
       Ide.Plugin.Ormolu
       Ide.Plugin.Pragmas
@@ -72,6 +73,7 @@ library
     , extra
     , filepath
     , floskell == 0.10.*
+    , fourmolu ^>= 0.1
     , ghc
     , ghc-boot-th
     , ghcide >= 0.1
@@ -101,11 +103,10 @@ library
   else
     build-depends:     unix
   if flag(agpl)
-    if impl(ghc < 8.10)
-      build-depends:
-        brittany
-      exposed-modules:
-        Ide.Plugin.Brittany
+    build-depends:
+      brittany
+    exposed-modules:
+      Ide.Plugin.Brittany
 
   ghc-options:
          -Wall
@@ -223,7 +224,7 @@ common hls-test-utils
                      , hslogger
                      , hspec
                      , hspec-core
-                     , lsp-test >= 0.11.0.3
+                     , lsp-test >= 0.11.0.4
                      , stm
                      , tasty-hunit
                      , temporary
@@ -252,7 +253,7 @@ test-suite func-test
                       , haskell-lsp
                       , haskell-lsp-types
                       , lens
-                      , lsp-test >= 0.11.0.3
+                      , lsp-test >= 0.11.0.4
                       , tasty
                       , tasty-ant-xml >= 1.1.6
                       , tasty-expected-failure
diff --git a/shell.nix b/shell.nix
index 7f0ffcc9be..076161c96f 100644
--- a/shell.nix
+++ b/shell.nix
@@ -42,6 +42,7 @@ let defaultCompiler = "ghc" + lib.replaceStrings ["."] [""] haskellPackages.ghc.
           data-default-instances-old-locale
           extra
           floskell
+          fourmolu
           fuzzy
           generic-deriving
           ghc-check
diff --git a/src/Ide/Plugin/Fourmolu.hs b/src/Ide/Plugin/Fourmolu.hs
new file mode 100644
index 0000000000..07d4272b95
--- /dev/null
+++ b/src/Ide/Plugin/Fourmolu.hs
@@ -0,0 +1,95 @@
+{-# LANGUAGE OverloadedStrings   #-}
+{-# LANGUAGE PackageImports      #-}
+{-# LANGUAGE RecordWildCards     #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TypeApplications    #-}
+
+module Ide.Plugin.Fourmolu
+  (
+    descriptor
+  , provider
+  )
+where
+
+import           Control.Exception
+import qualified Data.Text                         as T
+import           Development.IDE.Core.Rules
+import           Development.IDE.Core.RuleTypes    (GhcSession (GhcSession))
+import           Development.IDE.Core.Shake        (use)
+import           Development.IDE.GHC.Util          (hscEnv)
+import           Development.IDE.Types.Diagnostics as D
+import           Development.IDE.Types.Location
+import qualified DynFlags                          as D
+import qualified EnumSet                           as S
+import           GHC
+import           GHC.LanguageExtensions.Type
+import           GhcPlugins                        (HscEnv (hsc_dflags))
+import           Ide.Plugin.Formatter
+import           Ide.PluginUtils
+import           Ide.Types
+import           Language.Haskell.LSP.Core         (LspFuncs (withIndefiniteProgress),
+                                                    ProgressCancellable (Cancellable))
+import           Language.Haskell.LSP.Types
+import "fourmolu" Ormolu
+import           System.FilePath                   (takeFileName)
+import           Text.Regex.TDFA.Text              ()
+
+-- ---------------------------------------------------------------------
+
+descriptor :: PluginId -> PluginDescriptor
+descriptor plId = (defaultPluginDescriptor plId)
+  { pluginFormattingProvider = Just provider
+  }
+
+-- ---------------------------------------------------------------------
+
+provider :: FormattingProvider IO
+provider lf ideState typ contents fp _ = withIndefiniteProgress lf title Cancellable $ do
+  let
+    fromDyn :: DynFlags -> IO [DynOption]
+    fromDyn df =
+      let
+        pp =
+          let p = D.sPgm_F $ D.settings df
+          in  if null p then [] else ["-pgmF=" <> p]
+        pm = map (("-fplugin=" <>) . moduleNameString) $ D.pluginModNames df
+        ex = map showExtension $ S.toList $ D.extensionFlags df
+      in
+        return $ map DynOption $ pp <> pm <> ex
+
+  ghc <- runAction "Fourmolu" ideState $ use GhcSession fp
+  let df = hsc_dflags . hscEnv <$> ghc
+  fileOpts <- case df of
+          Nothing -> return []
+          Just df -> fromDyn df
+
+  let
+    fullRegion = RegionIndices Nothing Nothing
+    rangeRegion s e = RegionIndices (Just $ s + 1) (Just $ e + 1)
+    mkConf o region = do
+      printerOpts <- loadConfigFile True (Just fp') defaultPrinterOpts
+      return $ defaultConfig
+        { cfgDynOptions = o
+        , cfgRegion = region
+        , cfgDebug = True
+        , cfgPrinterOpts = printerOpts
+        }
+    fmt :: T.Text -> Config RegionIndices -> IO (Either OrmoluException T.Text)
+    fmt cont conf =
+      try @OrmoluException (ormolu conf fp' $ T.unpack cont)
+    fp' = fromNormalizedFilePath fp
+
+  case typ of
+    FormatText -> ret <$> (fmt contents =<< mkConf fileOpts fullRegion)
+    FormatRange (Range (Position sl _) (Position el _)) ->
+      ret <$> (fmt contents =<< mkConf fileOpts (rangeRegion sl el))
+ where
+  title = T.pack $ "Formatting " <> takeFileName (fromNormalizedFilePath fp)
+  ret :: Either OrmoluException T.Text -> Either ResponseError (List TextEdit)
+  ret (Left err) = Left
+    (responseError (T.pack $ "fourmoluCmd: " ++ show err) )
+  ret (Right new) = Right (makeDiffTextEdit contents new)
+
+showExtension :: Extension -> String
+showExtension Cpp   = "-XCPP"
+showExtension other = "-X" ++ show other
diff --git a/src/Ide/Plugin/Ormolu.hs b/src/Ide/Plugin/Ormolu.hs
index dcfad0b16a..e5d268232b 100644
--- a/src/Ide/Plugin/Ormolu.hs
+++ b/src/Ide/Plugin/Ormolu.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE OverloadedStrings   #-}
+{-# LANGUAGE PackageImports      #-}
 {-# LANGUAGE RecordWildCards     #-}
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeApplications    #-}
@@ -29,7 +30,7 @@ import           Ide.Types
 import           Language.Haskell.LSP.Core         (LspFuncs (withIndefiniteProgress),
                                                     ProgressCancellable (Cancellable))
 import           Language.Haskell.LSP.Types
-import           Ormolu
+import "ormolu"  Ormolu
 import           System.FilePath                   (takeFileName)
 import           Text.Regex.TDFA.Text              ()
 
diff --git a/stack-8.10.1.yaml b/stack-8.10.1.yaml
index 8d62e3c008..f1494f4265 100644
--- a/stack-8.10.1.yaml
+++ b/stack-8.10.1.yaml
@@ -8,19 +8,25 @@ ghc-options:
   "$everything": -haddock
 
 extra-deps:
+- aeson-1.5.2.0
+- github: bubba/brittany
+  commit: c59655f10d5ad295c2481537fc8abf0a297d9d1c
 - Cabal-3.0.2.0
 - hie-bios-0.6.1
 - cabal-plan-0.7.0.0
 - clock-0.7.2
-- floskell-0.10.3
+- data-tree-print-0.1.0.2
+- floskell-0.10.4
+- fourmolu-0.1.0.0@rev:1
 - ghc-exactprint-0.6.3
+- HsYAML-aeson-0.2.0.0@rev:2
 - lens-4.19.1
-- lsp-test-0.11.0.3
+- lsp-test-0.11.0.4
 - monad-dijkstra-0.1.1.2
 - optics-core-0.3
 - ormolu-0.1.2.0
 - retrie-0.1.1.1
-- stylish-haskell-0.11.0.0
+- stylish-haskell-0.11.0.3
 - semigroups-0.18.5
 - temporary-1.2.1.1
 - these-1.1
@@ -28,14 +34,11 @@ extra-deps:
 flags:
   haskell-language-server:
     pedantic: true
-    # We want to let agpl be the default value in .cabal (True)
-    # but brittany is not usable with ghc-8.10.1
-    # see https://github.com/lspitzner/brittany/issues/269
-    agpl: false
   retrie:
     BuildExecutable: false
 
-# allow-newer: true
+# for data-tree-print's bounds on base (>=4.8 && <4.14); using base-4.14.0.0.
+allow-newer: true
 
 nix:
   packages: [ icu libcxx zlib ]
diff --git a/stack-8.6.4.yaml b/stack-8.6.4.yaml
index 307f1a86b9..896254b08e 100644
--- a/stack-8.6.4.yaml
+++ b/stack-8.6.4.yaml
@@ -9,15 +9,18 @@ ghc-options:
   "$everything": -haddock
 
 extra-deps:
+- aeson-1.5.2.0
 - ansi-terminal-0.10.3
-- base-compat-0.11.0
-- brittany-0.12.1.1@rev:2
+- base-compat-0.10.5
+- github: bubba/brittany
+  commit: c59655f10d5ad295c2481537fc8abf0a297d9d1c
 - butcher-1.3.3.1
 - Cabal-3.0.2.0
 - cabal-plan-0.6.2.0
 - clock-0.7.2
 - extra-1.7.3
-- floskell-0.10.3
+- floskell-0.10.4
+- fourmolu-0.1.0.0@rev:1
 - fuzzy-0.1.0.0
 # - ghcide-0.1.0
 - ghc-check-0.5.0.1
@@ -30,16 +33,17 @@ extra-deps:
 - haskell-lsp-types-0.22.0.0
 - hie-bios-0.6.1
 - HsYAML-0.2.1.0@rev:1
-- HsYAML-aeson-0.2.0.0@rev:1
+- HsYAML-aeson-0.2.0.0@rev:2
 - indexed-profunctors-0.1
 - lens-4.18
-- lsp-test-0.11.0.3
+- lsp-test-0.11.0.4
 - monad-dijkstra-0.1.1.2
 - opentelemetry-0.4.2
 - optics-core-0.2
 - optparse-applicative-0.15.1.0
 - ormolu-0.1.2.0
 - parser-combinators-1.2.1
+- primitive-0.7.1.0
 - regex-base-0.94.0.0
 - regex-pcre-builtin-0.95.1.1.8.43
 - regex-tdfa-1.3.1.0
@@ -47,9 +51,10 @@ extra-deps:
 - semialign-1.1
 # - github: wz1000/shake
 #   commit: fb3859dca2e54d1bbb2c873e68ed225fa179fbef
-- stylish-haskell-0.11.0.0
+- stylish-haskell-0.11.0.3
 - tasty-rerun-1.1.17
 - temporary-1.2.1.1
+- these-1.1.1.1
 - type-equality-1
 - topograph-1
 
diff --git a/stack-8.6.5.yaml b/stack-8.6.5.yaml
index fe45cb734a..605591b432 100644
--- a/stack-8.6.5.yaml
+++ b/stack-8.6.5.yaml
@@ -8,15 +8,18 @@ ghc-options:
   "$everything": -haddock
 
 extra-deps:
+- aeson-1.5.2.0
 - ansi-terminal-0.10.3
-- base-compat-0.11.0
-- brittany-0.12.1.1@rev:2
+- base-compat-0.10.5
+- github: bubba/brittany
+  commit: c59655f10d5ad295c2481537fc8abf0a297d9d1c
 - butcher-1.3.3.1
 - Cabal-3.0.2.0
 - cabal-plan-0.6.2.0
 - clock-0.7.2
 - extra-1.7.3
-- floskell-0.10.3
+- floskell-0.10.4
+- fourmolu-0.1.0.0@rev:1
 - fuzzy-0.1.0.0
 # - ghcide-0.1.0
 - ghc-check-0.5.0.1
@@ -29,16 +32,17 @@ extra-deps:
 - haskell-lsp-types-0.22.0.0
 - hie-bios-0.6.1
 - HsYAML-0.2.1.0@rev:1
-- HsYAML-aeson-0.2.0.0@rev:1
+- HsYAML-aeson-0.2.0.0@rev:2
 - indexed-profunctors-0.1
 - lens-4.18
-- lsp-test-0.11.0.3
+- lsp-test-0.11.0.4
 - monad-dijkstra-0.1.1.2
 - opentelemetry-0.4.2
 - optics-core-0.2
 - optparse-applicative-0.15.1.0
 - ormolu-0.1.2.0
 - parser-combinators-1.2.1
+- primitive-0.7.1.0
 - regex-base-0.94.0.0
 - regex-pcre-builtin-0.95.1.1.8.43
 - regex-tdfa-1.3.1.0
@@ -46,9 +50,10 @@ extra-deps:
 - semialign-1.1
 # - github: wz1000/shake
 #   commit: fb3859dca2e54d1bbb2c873e68ed225fa179fbef
-- stylish-haskell-0.11.0.0
+- stylish-haskell-0.11.0.3
 - tasty-rerun-1.1.17
 - temporary-1.2.1.1
+- these-1.1.1.1
 - type-equality-1
 - topograph-1
 
diff --git a/stack-8.8.2.yaml b/stack-8.8.2.yaml
index 0d3b2d5ca3..131969fa4c 100644
--- a/stack-8.8.2.yaml
+++ b/stack-8.8.2.yaml
@@ -8,14 +8,17 @@ ghc-options:
   "$everything": -haddock
 
 extra-deps:
+- aeson-1.5.2.0
 - apply-refact-0.7.0.0
-- brittany-0.12.1.1
+- github: bubba/brittany
+  commit: c59655f10d5ad295c2481537fc8abf0a297d9d1c
 - butcher-1.3.3.2
 - bytestring-trie-0.2.5.0
 - clock-0.7.2
 - constrained-dynamic-0.1.0.0
 - extra-1.7.3
-- floskell-0.10.3
+- floskell-0.10.4
+- fourmolu-0.1.0.0@rev:1
 # - ghcide-0.1.0
 - ghc-check-0.5.0.1
 - ghc-lib-parser-8.10.1.20200523
@@ -29,9 +32,9 @@ extra-deps:
 - hoogle-5.0.17.11
 - hsimport-0.11.0
 - HsYAML-0.2.1.0@rev:1
-- HsYAML-aeson-0.2.0.0@rev:1
+- HsYAML-aeson-0.2.0.0@rev:2
 - ilist-0.3.1.0
-- lsp-test-0.11.0.3
+- lsp-test-0.11.0.4
 - monad-dijkstra-0.1.1.2
 - opentelemetry-0.4.2
 - ormolu-0.1.2.0
@@ -39,8 +42,9 @@ extra-deps:
 - semigroups-0.18.5
 # - github: wz1000/shake
 #   commit: fb3859dca2e54d1bbb2c873e68ed225fa179fbef
-- stylish-haskell-0.11.0.0
+- stylish-haskell-0.11.0.3
 - temporary-1.2.1.1
+- these-1.1.1.1
 
 flags:
   haskell-language-server:
diff --git a/stack-8.8.3.yaml b/stack-8.8.3.yaml
index 71a81374c1..c52d3afe2a 100644
--- a/stack-8.8.3.yaml
+++ b/stack-8.8.3.yaml
@@ -8,26 +8,32 @@ ghc-options:
   "$everything": -haddock
 
 extra-deps:
+- aeson-1.5.2.0
 - apply-refact-0.7.0.0
+- github: bubba/brittany
+  commit: c59655f10d5ad295c2481537fc8abf0a297d9d1c
 - bytestring-trie-0.2.5.0
 - cabal-plan-0.6.2.0
 - clock-0.7.2
 - constrained-dynamic-0.1.0.0
 - extra-1.7.3
-- floskell-0.10.3
+- floskell-0.10.4
+- fourmolu-0.1.0.0@rev:1
 # - ghcide-0.1.0
 - haskell-src-exts-1.21.1
 - hie-bios-0.6.1
 - hlint-2.2.8
+- HsYAML-aeson-0.2.0.0@rev:2
 - hoogle-5.0.17.11
 - hsimport-0.11.0
 - ilist-0.3.1.0
-- lsp-test-0.11.0.3
+- lsp-test-0.11.0.4
 - monad-dijkstra-0.1.1.2
 - retrie-0.1.1.1
 - semigroups-0.18.5
 # - github: wz1000/shake
 #   commit: fb3859dca2e54d1bbb2c873e68ed225fa179fbef
+- stylish-haskell-0.11.0.3
 - temporary-1.2.1.1
 
 flags:
diff --git a/stack-8.8.4.yaml b/stack-8.8.4.yaml
index d2f1d8449a..08ce987d48 100644
--- a/stack-8.8.4.yaml
+++ b/stack-8.8.4.yaml
@@ -9,25 +9,31 @@ ghc-options:
   "$everything": -haddock
 
 extra-deps:
+- aeson-1.5.2.0
 - apply-refact-0.7.0.0
+- github: bubba/brittany
+  commit: c59655f10d5ad295c2481537fc8abf0a297d9d1c
 - bytestring-trie-0.2.5.0
 - cabal-helper-1.1.0.0
 - cabal-plan-0.6.2.0
 - clock-0.7.2
 - constrained-dynamic-0.1.0.0
 - extra-1.7.3
-- floskell-0.10.3
+- floskell-0.10.4
+- fourmolu-0.1.0.0@rev:1
 # - ghcide-0.1.0
 - haskell-src-exts-1.21.1
 - hie-bios-0.6.1
 - hlint-2.2.8
+- HsYAML-aeson-0.2.0.0@rev:2
 - hoogle-5.0.17.11
 - hsimport-0.11.0
 - ilist-0.3.1.0
-- lsp-test-0.11.0.3
+- lsp-test-0.11.0.4
 - monad-dijkstra-0.1.1.2
 - retrie-0.1.1.1
 - semigroups-0.18.5
+- stylish-haskell-0.11.0.3
 # - github: wz1000/shake
 #   commit: fb3859dca2e54d1bbb2c873e68ed225fa179fbef
 - temporary-1.2.1.1
diff --git a/stack.yaml b/stack.yaml
index a3fb790819..2350fff2d5 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -8,15 +8,18 @@ ghc-options:
   "$everything": -haddock
 
 extra-deps:
+- aeson-1.5.2.0
 - ansi-terminal-0.10.3
 - base-compat-0.11.0
-- brittany-0.12.1.1@rev:2
+- github: bubba/brittany
+  commit: c59655f10d5ad295c2481537fc8abf0a297d9d1c
 - butcher-1.3.3.1
 - Cabal-3.0.2.0
 - cabal-plan-0.6.2.0
 - clock-0.7.2
 - extra-1.7.3
-- floskell-0.10.3
+- floskell-0.10.4
+- fourmolu-0.1.0.0@rev:1
 - fuzzy-0.1.0.0
 # - ghcide-0.1.0
 - ghc-check-0.5.0.1
@@ -29,10 +32,10 @@ extra-deps:
 - haskell-lsp-types-0.22.0.0
 - hie-bios-0.6.1
 - HsYAML-0.2.1.0@rev:1
-- HsYAML-aeson-0.2.0.0@rev:1
+- HsYAML-aeson-0.2.0.0@rev:2
 - indexed-profunctors-0.1
 - lens-4.18
-- lsp-test-0.11.0.3
+- lsp-test-0.11.0.4
 - monad-dijkstra-0.1.1.2
 - opentelemetry-0.4.2
 - optics-core-0.2
@@ -44,7 +47,7 @@ extra-deps:
 - regex-tdfa-1.3.1.0
 - retrie-0.1.1.1
 - semialign-1.1
-- stylish-haskell-0.11.0.0
+- stylish-haskell-0.11.0.3
 - tasty-rerun-1.1.17
 - temporary-1.2.1.1
 - type-equality-1
diff --git a/test/functional/Format.hs b/test/functional/Format.hs
index 11fc65123d..0bb2ee4944 100644
--- a/test/functional/Format.hs
+++ b/test/functional/Format.hs
@@ -12,8 +12,7 @@ import Test.Tasty
 import Test.Tasty.Golden
 import Test.Tasty.HUnit
 
-#if MIN_VERSION_GLASGOW_HASKELL(8,10,0,0) || !defined(AGPL)
-#else
+#if AGPL
 import qualified Data.Text.IO as T
 #endif
 
@@ -30,12 +29,11 @@ tests = testGroup "format document" [
     , rangeTests
     , providerTests
     , stylishHaskellTests
--- There's no Brittany formatter on the 8.10.1 builds (yet)
-#if MIN_VERSION_GLASGOW_HASKELL(8,10,0,0) || !defined(AGPL)
-#else
+#if AGPL
     , brittanyTests
 #endif
     , ormoluTests
+    , fourmoluTests
     ]
 
 rangeTests :: TestTree
@@ -62,9 +60,7 @@ providerTests = testGroup "formatting provider" [
         formatRange doc (FormattingOptions 2 True) (Range (Position 1 0) (Position 3 10))
         documentContents doc >>= liftIO . (@?= orig)
 
--- There's no Brittany formatter on the 8.10.1 builds (yet)
-#if MIN_VERSION_GLASGOW_HASKELL(8,10,0,0) || !defined(AGPL)
-#else
+#if AGPL
     , testCase "can change on the fly" $ runSession hieCommand fullCaps "test/testdata" $ do
         formattedBrittany <- liftIO $ T.readFile "test/testdata/Format.brittany.formatted.hs"
         formattedFloskell <- liftIO $ T.readFile "test/testdata/Format.floskell.formatted.hs"
@@ -113,8 +109,7 @@ stylishHaskellTests = testGroup "stylish-haskell" [
       BS.fromStrict . T.encodeUtf8 <$> documentContents doc
   ]
 
-#if MIN_VERSION_GLASGOW_HASKELL(8,10,0,0) || !defined(AGPL)
-#else
+#if AGPL
 brittanyTests :: TestTree
 brittanyTests = testGroup "brittany" [
     goldenVsStringDiff "formats a document with LF endings" goldenGitDiff "test/testdata/BrittanyLF.formatted_document.hs" $ runSession hieCommand fullCaps "test/testdata" $ do
@@ -159,11 +154,24 @@ ormoluTests = testGroup "ormolu"
       BS.fromStrict . T.encodeUtf8 <$> documentContents doc
   ]
 
+fourmoluTests :: TestTree
+fourmoluTests = testGroup "fourmolu"
+  [ goldenVsStringDiff "formats correctly" goldenGitDiff "test/testdata/Format.fourmolu.formatted.hs" $ runSession hieCommand fullCaps "test/testdata" $ do
+      sendNotification WorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfig "fourmolu"))
+      doc <- openDoc "Format.hs" "haskell"
+      formatDoc doc (FormattingOptions 4 True)
+      BS.fromStrict . T.encodeUtf8 <$> documentContents doc
+  , goldenVsStringDiff "formats imports correctly" goldenGitDiff "test/testdata/Format2.fourmolu.formatted.hs" $ runSession hieCommand fullCaps "test/testdata" $ do
+      sendNotification WorkspaceDidChangeConfiguration (DidChangeConfigurationParams (formatLspConfig "fourmolu"))
+      doc <- openDoc "Format2.hs" "haskell"
+      formatDoc doc (FormattingOptions 4 True)
+      BS.fromStrict . T.encodeUtf8 <$> documentContents doc
+  ]
+
 formatLspConfig :: Value -> Value
 formatLspConfig provider = object [ "haskell" .= object ["formattingProvider" .= (provider :: Value)] ]
 
-#if MIN_VERSION_GLASGOW_HASKELL(8,10,0,0) || !defined(AGPL)
-#else
+#if AGPL
 -- | The same as 'formatLspConfig' but using the legacy section name
 formatLspConfigOld :: Value -> Value
 formatLspConfigOld provider = object [ "languageServerHaskell" .= object ["formattingProvider" .= (provider :: Value)] ]
diff --git a/test/testdata/Format.brittany.formatted.hs b/test/testdata/Format.brittany.formatted.hs
index d3da590142..9ecc458524 100644
--- a/test/testdata/Format.brittany.formatted.hs
+++ b/test/testdata/Format.brittany.formatted.hs
@@ -11,5 +11,8 @@ bar s = do
   x <- return "hello"
   return "asdf"
 
-data Baz = Baz { a :: Int, b :: String }
+data Baz = Baz
+  { a :: Int
+  , b :: String
+  }
 
diff --git a/test/testdata/Format.brittany_post_floskell.formatted.hs b/test/testdata/Format.brittany_post_floskell.formatted.hs
index 02de9c673d..9cbb33715c 100644
--- a/test/testdata/Format.brittany_post_floskell.formatted.hs
+++ b/test/testdata/Format.brittany_post_floskell.formatted.hs
@@ -13,5 +13,8 @@ bar s = do
   x <- return "hello"
   return "asdf"
 
-data Baz = Baz { a :: Int, b :: String }
+data Baz = Baz
+  { a :: Int
+  , b :: String
+  }
 
diff --git a/test/testdata/Format.fourmolu.formatted.hs b/test/testdata/Format.fourmolu.formatted.hs
new file mode 100644
index 0000000000..41dba5b34d
--- /dev/null
+++ b/test/testdata/Format.fourmolu.formatted.hs
@@ -0,0 +1,16 @@
+module Format where
+
+import Data.Int
+import Data.List
+import Prelude
+
+foo :: Int -> Int
+foo 3 = 2
+foo x = x
+
+bar :: String -> IO String
+bar s = do
+    x <- return "hello"
+    return "asdf"
+
+data Baz = Baz {a :: Int, b :: String}
diff --git a/test/testdata/Format2.fourmolu.formatted.hs b/test/testdata/Format2.fourmolu.formatted.hs
new file mode 100644
index 0000000000..b3d867e700
--- /dev/null
+++ b/test/testdata/Format2.fourmolu.formatted.hs
@@ -0,0 +1,5 @@
+import Data.Bool
+import Data.Char
+import Data.Data
+import Data.Either
+import Data.Int