diff --git a/Makefile b/Makefile
index 98b4eda..767ca25 100644
--- a/Makefile
+++ b/Makefile
@@ -2,7 +2,7 @@ script=dist/main.js
 
 .PHONY: format
 format:
-	git ls-files '*.hs' | xargs fourmolu -i
+	git ls-files '*.hs' | xargs fourmolu -i --unsafe
 	cabal-fmt --inplace fundeps.cabal
 
 .PHONY: client
diff --git a/fourmolu.yaml b/fourmolu.yaml
index 5d76a88..fda9892 100644
--- a/fourmolu.yaml
+++ b/fourmolu.yaml
@@ -2,8 +2,17 @@ indentation: 4
 comma-style: leading # for lists, tuples etc. - can also be 'trailing'
 record-brace-space: false # rec {x = 1} vs. rec{x = 1}
 indent-wheres: false # 'false' means save space by only half-indenting the 'where' keyword
-diff-friendly-import-export: false # 'false' uses Ormolu-style lists
 respectful: true # don't be too opinionated about newlines etc.
 haddock-style: multi-line # '--' vs. '{-'
+haddock-style-module: multi-line
 newlines-between-decls: 2 # number of newlines between top-level declarations
-import-export-comma-style: leading
+import-export-style: leading
+let-style: auto
+in-style: right-align
+fixities:
+  - infixl 5 .= # both in tomland (fixyty 5) and aeson (fixity 8)
+unicode: never
+column-limit: none # Disclaimer: enabling column-limit breaks idempotence in a few cases.
+function-arrows: trailing
+single-constraint-parens: never
+
diff --git a/fundeps-hs/Main.hs b/fundeps-hs/Main.hs
index 693268f..2350c81 100644
--- a/fundeps-hs/Main.hs
+++ b/fundeps-hs/Main.hs
@@ -1,6 +1,6 @@
 module Main (main) where
 
-import qualified FunDeps
+import FunDeps qualified
 
 
 main :: IO ()
diff --git a/fundeps.cabal b/fundeps.cabal
index d550635..8f80837 100644
--- a/fundeps.cabal
+++ b/fundeps.cabal
@@ -17,7 +17,7 @@ description:
 category:           Web
 build-type:         Simple
 extra-source-files: README.md
-tested-with:        GHC ==8.10.3
+tested-with:        GHC ==9.2.8
 
 source-repository head
   type:     git
@@ -30,8 +30,7 @@ flag WithJS
 
 common common-options
   build-depends:    base >=4.7 && <5
-  default-language: Haskell2010
-  default-extensions: ImportQualifiedPost
+  default-language: GHC2021
   ghc-options:
     -fwrite-ide-info -hiedir=hie -Wall -Wcompat -Widentities
     -Wincomplete-record-updates -Wincomplete-uni-patterns
diff --git a/fundeps/Main.hs b/fundeps/Main.hs
index 1aeec57..058cf80 100644
--- a/fundeps/Main.hs
+++ b/fundeps/Main.hs
@@ -2,7 +2,7 @@
 
 module Main (main) where
 
-import qualified FunDeps
+import FunDeps qualified
 import Turtle
 
 
diff --git a/src/FunDeps/Server.hs b/src/FunDeps/Server.hs
index 5d1b621..9913a3e 100644
--- a/src/FunDeps/Server.hs
+++ b/src/FunDeps/Server.hs
@@ -7,6 +7,7 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE TypeOperators #-}
+
 #ifdef WithJS
 {-# LANGUAGE TemplateHaskell #-}
 #endif
diff --git a/test/Spec.hs b/test/Spec.hs
index f7cd9b0..f547722 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -1,4 +1,4 @@
-import qualified TUI.CommandsSpec
+import TUI.CommandsSpec qualified
 import Test.Hspec
 
 
diff --git a/test/TUI/CommandsSpec.hs b/test/TUI/CommandsSpec.hs
index 434468e..4d91177 100644
--- a/test/TUI/CommandsSpec.hs
+++ b/test/TUI/CommandsSpec.hs
@@ -3,7 +3,7 @@
 module TUI.CommandsSpec (spec) where
 
 import Data.Declaration
-import qualified Data.GraphViz.Commands as Gv
+import Data.GraphViz.Commands qualified as Gv
 import TUI.Commands (Command (..), CommandParseError (..), QueryItem (..), parseCommand)
 import Test.Hspec