diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,5 +1,8 @@
 # CHANGELOG
 
+- 0.15.1.0 (2025-04-13)
+     *  #491 Support GHC 9.12 (By GuillaumedeVolpiano)
+
 - 0.15.0.1 (2025-04-13)
      *  #493 Support Cabal 3.12 again (By GuillaumedeVolpiano)
 
diff --git a/lib/Language/Haskell/Stylish/Comments.hs b/lib/Language/Haskell/Stylish/Comments.hs
--- a/lib/Language/Haskell/Stylish/Comments.hs
+++ b/lib/Language/Haskell/Stylish/Comments.hs
@@ -61,7 +61,7 @@
     commentsWithLines :: [(LineBlock, GHC.LEpaComment)]
     commentsWithLines = do
         comment <- allComments
-        let s = GHC.anchor $ GHC.getLoc comment
+        let s = GHC.epaLocationRealSrcSpan $ GHC.getLoc comment
         pure (realSrcSpanToLineBlock s, comment)
 
     work
diff --git a/lib/Language/Haskell/Stylish/Config/Cabal.hs b/lib/Language/Haskell/Stylish/Config/Cabal.hs
--- a/lib/Language/Haskell/Stylish/Config/Cabal.hs
+++ b/lib/Language/Haskell/Stylish/Config/Cabal.hs
@@ -53,7 +53,7 @@
   go searched (p : ps) = do
 
 #if MIN_VERSION_Cabal(3,14,0)
-    let projectRoot = Just $ makeSymbolicPath p
+    let projectRoot = Just $ Cabal.makeSymbolicPath p
     potentialCabalFile <- Cabal.findPackageDesc projectRoot
 #else
     potentialCabalFile <- Cabal.findPackageDesc p
diff --git a/lib/Language/Haskell/Stylish/GHC.hs b/lib/Language/Haskell/Stylish/GHC.hs
--- a/lib/Language/Haskell/Stylish/GHC.hs
+++ b/lib/Language/Haskell/Stylish/GHC.hs
@@ -86,6 +86,6 @@
 deepAnnComments = everything (++) (mkQ [] priorAndFollowing)
 
 priorAndFollowing :: GHC.EpAnnComments -> [GHC.LEpaComment]
-priorAndFollowing = sortOn (GHC.anchor . GHC.getLoc) . \case
+priorAndFollowing = sortOn (GHC.epaLocationRealSrcSpan . GHC.getLoc) . \case
     GHC.EpaComments         {..} -> priorComments
     GHC.EpaCommentsBalanced {..} -> priorComments ++ followingComments
diff --git a/lib/Language/Haskell/Stylish/Module.hs b/lib/Language/Haskell/Stylish/Module.hs
--- a/lib/Language/Haskell/Stylish/Module.hs
+++ b/lib/Language/Haskell/Stylish/Module.hs
@@ -141,7 +141,7 @@
     prag comment = case GHC.ac_tok (GHC.unLoc comment) of
         GHC.EpaBlockComment str
             | lang : p1 : ps <- tokenize str, map toLower lang == "language" ->
-                pure (GHC.anchor (GHC.getLoc comment), p1 :| ps)
+                pure (GHC.epaLocationRealSrcSpan (GHC.getLoc comment), p1 :| ps)
         _ -> Nothing
 
     tokenize = words .
diff --git a/lib/Language/Haskell/Stylish/Printer.hs b/lib/Language/Haskell/Stylish/Printer.hs
--- a/lib/Language/Haskell/Stylish/Printer.hs
+++ b/lib/Language/Haskell/Stylish/Printer.hs
@@ -53,6 +53,7 @@
 import           GHC.Types.Name.Reader           (RdrName (..))
 import           GHC.Types.SrcLoc                (GenLocated (..))
 import qualified GHC.Types.SrcLoc                as GHC
+import           GHC.TypeLits                    (symbolVal)
 import           GHC.Utils.Outputable            (Outputable)
 
 --------------------------------------------------------------------------------
@@ -160,18 +161,19 @@
 
 nameAnnAdornment :: GHC.NameAnn -> (String, String)
 nameAnnAdornment = \case
-    GHC.NameAnn {..}       -> fromAdornment nann_adornment
-    GHC.NameAnnCommas {..} -> fromAdornment nann_adornment
-    GHC.NameAnnBars {..}   -> fromAdornment nann_adornment
-    GHC.NameAnnOnly {..}   -> fromAdornment nann_adornment
+    GHC.NameAnn {GHC.nann_adornment = na}       -> fromAdornment na
+    GHC.NameAnnCommas {GHC.nann_adornment = na}       -> fromAdornment na
+    GHC.NameAnnBars {GHC.nann_parensh = (o, c)}       -> fromAdornment (GHC.NameParensHash o c)
+    GHC.NameAnnOnly {GHC.nann_adornment = na}       -> fromAdornment na
     GHC.NameAnnRArrow {}   -> (mempty, mempty)
     GHC.NameAnnQuote {}    -> ("'", mempty)
     GHC.NameAnnTrailing {} -> (mempty, mempty)
   where
-    fromAdornment GHC.NameParens     = ("(", ")")
-    fromAdornment GHC.NameBackquotes = ("`", "`")
-    fromAdornment GHC.NameParensHash = ("#(", "#)")
-    fromAdornment GHC.NameSquare     = ("[", "]")
+    fromAdornment (GHC.NameParens l r)     = (symbolVal l, symbolVal r)
+    fromAdornment (GHC.NameBackquotes l r) = (symbolVal l, symbolVal r)
+    fromAdornment (GHC.NameParensHash l r) = (symbolVal l, symbolVal r)
+    fromAdornment (GHC.NameSquare l r)     = (symbolVal l, symbolVal r)
+    fromAdornment GHC.NameNoAdornment      = (mempty, mempty)
 
 -- | Print module name
 putModuleName :: GHC.ModuleName -> P ()
@@ -197,7 +199,7 @@
       (comma >> space)
       (fmap putType xs)
     putText "]"
-  GHC.HsExplicitTupleTy _ xs -> do
+  GHC.HsExplicitTupleTy _ _ xs -> do
     putText "'("
     sep
       (comma >> space)
diff --git a/lib/Language/Haskell/Stylish/Step/Data.hs b/lib/Language/Haskell/Stylish/Step/Data.hs
--- a/lib/Language/Haskell/Stylish/Step/Data.hs
+++ b/lib/Language/Haskell/Stylish/Step/Data.hs
@@ -103,6 +103,8 @@
         isAfterStart :: GHC.LEpaComment -> Bool
         isAfterStart (GHC.L (GHC.EpaSpan (GHC.RealSrcSpan commentSpan _)) _) =
                GHC.srcSpanStartLine commentSpan >= GHC.srcSpanStartLine declSpan
+        isAfterStart (GHC.L (GHC.EpaDelta (GHC.RealSrcSpan commentSpan _) _ _) _) =
+               GHC.srcSpanStartLine commentSpan >= GHC.srcSpanStartLine declSpan
         isAfterStart _ = False
 
     dataDecls :: Module -> [DataDecl]
diff --git a/lib/Language/Haskell/Stylish/Step/Imports.hs b/lib/Language/Haskell/Stylish/Step/Imports.hs
--- a/lib/Language/Haskell/Stylish/Step/Imports.hs
+++ b/lib/Language/Haskell/Stylish/Step/Imports.hs
@@ -638,7 +638,7 @@
   prepareInner :: GHC.IE GHC.GhcPs -> GHC.IE GHC.GhcPs
   prepareInner = \case
     -- Simplify `A ()` to `A`.
-    GHC.IEThingWith x n GHC.NoIEWildcard [] md -> GHC.IEThingAbs x n md
+    GHC.IEThingWith x n GHC.NoIEWildcard [] md -> GHC.IEThingAbs (fst x) n md
     GHC.IEThingWith x n w ns md ->
       GHC.IEThingWith x n w (sortBy (compareWrappedName `on` GHC.unLoc) ns) md
     ie -> ie
diff --git a/lib/Language/Haskell/Stylish/Step/LanguagePragmas.hs b/lib/Language/Haskell/Stylish/Step/LanguagePragmas.hs
--- a/lib/Language/Haskell/Stylish/Step/LanguagePragmas.hs
+++ b/lib/Language/Haskell/Stylish/Step/LanguagePragmas.hs
@@ -198,5 +198,5 @@
 
     getMatchStrict :: GHC.Match GHC.GhcPs (GHC.LHsExpr GHC.GhcPs) -> [()]
     getMatchStrict (GHC.Match _ ctx _ _) = case ctx of
-      GHC.FunRhs _ _ GHC.SrcStrict -> [()]
-      _                            -> []
+      GHC.FunRhs _ _ GHC.SrcStrict _ -> [()]
+      _                              -> []
diff --git a/lib/Language/Haskell/Stylish/Step/ModuleHeader.hs b/lib/Language/Haskell/Stylish/Step/ModuleHeader.hs
--- a/lib/Language/Haskell/Stylish/Step/ModuleHeader.hs
+++ b/lib/Language/Haskell/Stylish/Step/ModuleHeader.hs
@@ -81,18 +81,18 @@
                 loc <- GHC.getLocA <$> GHC.hsmodExports modul
                 GHC.srcSpanEndLine <$> GHC.srcSpanToRealSrcSpan loc)
 
-        keywordLine kw = listToMaybe $ do
+        keywordLine kw = do
             GHC.EpAnn {..} <- pure $ GHC.hsmodAnn $ GHC.hsmodExt modul
-            GHC.AddEpAnn kw' (GHC.EpaSpan (GHC.RealSrcSpan s _)) <- GHC.am_main anns
-            guard $ kw == kw'
-            pure $ GHC.srcSpanEndLine s
+            case kw anns of
+              GHC.EpTok (GHC.EpaSpan (GHC.RealSrcSpan s _)) -> Just . GHC.srcSpanEndLine $ s
+              _ -> Nothing
 
-        moduleLine = keywordLine GHC.AnnModule
-        whereLine = keywordLine GHC.AnnWhere
+        moduleLine = keywordLine GHC.am_mod
+        whereLine = keywordLine GHC.am_where
 
         commentOnLine l = listToMaybe $ do
             comment <- epAnnComments $ GHC.hsmodAnn $ GHC.hsmodExt modul
-            guard $ GHC.srcSpanStartLine (GHC.anchor $ GHC.getLoc comment) == l
+            guard $ GHC.srcSpanStartLine (GHC.epaLocationRealSrcSpan $ GHC.getLoc comment) == l
             pure comment
 
         moduleComment = moduleLine >>= commentOnLine
@@ -152,7 +152,7 @@
                 attachModuleComment
             Single  | [egroup] <- exports
                     , not (commentGroupHasComments egroup)
-                    , [(export, _)] <- (cgItems egroup) -> do
+                    , [(export, _)] <- cgItems egroup -> do
                 printSingleLineExportList conf [export]
                 attachModuleComment
             Inline  | [] <- exports -> do
diff --git a/lib/Language/Haskell/Stylish/Step/SimpleAlign.hs b/lib/Language/Haskell/Stylish/Step/SimpleAlign.hs
--- a/lib/Language/Haskell/Stylish/Step/SimpleAlign.hs
+++ b/lib/Language/Haskell/Stylish/Step/SimpleAlign.hs
@@ -112,7 +112,7 @@
 matchToAlignable
     :: GHC.LocatedA (Hs.Match Hs.GhcPs (Hs.LHsExpr Hs.GhcPs))
     -> Maybe (Either (Alignable GHC.RealSrcSpan) (Alignable GHC.RealSrcSpan))
-matchToAlignable (GHC.L matchLoc m@(Hs.Match _ Hs.CaseAlt pats@(_ : _) grhss)) = do
+matchToAlignable (GHC.L matchLoc m@(Hs.Match _ Hs.CaseAlt (GHC.L _ pats@(_ : _)) grhss)) = do
   let patsLocs   = map GHC.getLocA pats
       pat        = last patsLocs
       guards     = getGuards m
@@ -128,7 +128,7 @@
     , aRight     = rightPos
     , aRightLead = length "-> "
     }
-matchToAlignable (GHC.L matchLoc (Hs.Match _ (Hs.FunRhs name _ _) pats@(_ : _) grhss)) = do
+matchToAlignable (GHC.L matchLoc (Hs.Match _ (Hs.FunRhs name _ _ _) (GHC.L _ pats@(_ : _)) grhss)) = do
   body <- unguardedRhsBody grhss
   let patsLocs = map GHC.getLocA pats
       nameLoc  = GHC.getLocA name
diff --git a/lib/Language/Haskell/Stylish/Step/Squash.hs b/lib/Language/Haskell/Stylish/Step/Squash.hs
--- a/lib/Language/Haskell/Stylish/Step/Squash.hs
+++ b/lib/Language/Haskell/Stylish/Step/Squash.hs
@@ -1,4 +1,5 @@
 --------------------------------------------------------------------------------
+{-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE PartialTypeSignatures #-}
 {-# LANGUAGE PatternGuards         #-}
 {-# LANGUAGE RecordWildCards       #-}
@@ -9,7 +10,6 @@
 
 
 --------------------------------------------------------------------------------
-import           Data.Maybe                      (listToMaybe)
 import qualified GHC.Hs                          as GHC
 import qualified GHC.Types.SrcLoc                as GHC
 
@@ -45,10 +45,9 @@
 
 
 --------------------------------------------------------------------------------
-fieldDeclSeparator :: [GHC.AddEpAnn]-> Maybe GHC.RealSrcSpan
-fieldDeclSeparator anns = listToMaybe $ do
-    GHC.AddEpAnn GHC.AnnDcolon (GHC.EpaSpan (GHC.RealSrcSpan s _)) <- anns
-    pure s
+fieldDeclSeparator :: GHC.EpUniToken "::" "\8759" -> Maybe GHC.RealSrcSpan
+fieldDeclSeparator (GHC.EpUniTok (GHC.EpaSpan (GHC.RealSrcSpan s _)) _) = Just s
+fieldDeclSeparator _ = Nothing
 
 
 --------------------------------------------------------------------------------
@@ -65,23 +64,23 @@
   where
     match = GHC.unLoc lmatch
     mbLeft = case match of
-        GHC.Match _ (GHC.FunRhs name _ _) [] _ ->
+        GHC.Match _ (GHC.FunRhs name _ _ _ ) (GHC.L _ []) _ ->
             GHC.srcSpanToRealSrcSpan $ GHC.getLocA name
-        GHC.Match _ _ pats@(_ : _) _ ->
+        GHC.Match _ _ (GHC.L _ pats@(_ : _)) _ ->
             GHC.srcSpanToRealSrcSpan . GHC.getLocA $ last pats
         _ -> Nothing
 
 
 --------------------------------------------------------------------------------
 matchSeparator :: GHC.EpAnn GHC.GrhsAnn -> Maybe GHC.RealSrcSpan
-matchSeparator GHC.EpAnn {..}
-    | GHC.AddEpAnn _ (GHC.EpaSpan (GHC.RealSrcSpan s _)) <- GHC.ga_sep anns = Just s
-matchSeparator _ = Nothing
-
+matchSeparator GHC.EpAnn {..} = case GHC.ga_sep anns of
+                                  Left (GHC.EpTok (GHC.EpaSpan (GHC.RealSrcSpan s _))) -> Just s
+                                  Right (GHC.EpUniTok (GHC.EpaSpan (GHC.RealSrcSpan s _)) _) -> Just s
+                                  _ -> Nothing
 
 --------------------------------------------------------------------------------
 step :: Step
-step = makeStep "Squash" $ \ls (module') ->
+step = makeStep "Squash" $ \ls module' ->
     let changes =
             foldMap squashFieldDecl (everything module') <>
             foldMap squashMatch (everything module') in
diff --git a/lib/Language/Haskell/Stylish/Step/UnicodeSyntax.hs b/lib/Language/Haskell/Stylish/Step/UnicodeSyntax.hs
--- a/lib/Language/Haskell/Stylish/Step/UnicodeSyntax.hs
+++ b/lib/Language/Haskell/Stylish/Step/UnicodeSyntax.hs
@@ -24,7 +24,7 @@
         Editor.replaceRealSrcSpan (GHC.epaLocationRealSrcSpan epaLoc) "→"
 hsTyReplacements (GHC.HsQualTy _ ctx _)
     | Just arrow <- GHC.ac_darrow . GHC.anns $ GHC.getLoc ctx
-    , (GHC.NormalSyntax, GHC.EpaSpan (GHC.RealSrcSpan loc _)) <- arrow =
+    , (GHC.EpUniTok (GHC.EpaSpan (GHC.RealSrcSpan loc _)) GHC.NormalSyntax) <- arrow =
         Editor.replaceRealSrcSpan loc "⇒"
 hsTyReplacements _ = mempty
 
@@ -32,7 +32,7 @@
 --------------------------------------------------------------------------------
 hsSigReplacements :: GHC.Sig GHC.GhcPs -> Editor.Edits
 hsSigReplacements (GHC.TypeSig ann _ _)
-    | GHC.AddEpAnn GHC.AnnDcolon epaLoc <- GHC.asDcolon ann
+    | GHC.EpUniTok epaLoc _ <- GHC.asDcolon ann
     , GHC.EpaSpan (GHC.RealSrcSpan loc _) <- epaLoc =
         Editor.replaceRealSrcSpan loc "∷"
 hsSigReplacements _ = mempty
diff --git a/stylish-haskell.cabal b/stylish-haskell.cabal
--- a/stylish-haskell.cabal
+++ b/stylish-haskell.cabal
@@ -1,6 +1,6 @@
 Cabal-version: 2.4
 Name:          stylish-haskell
-Version:       0.15.0.1
+Version:       0.15.1.0
 Synopsis:      Haskell code prettifier
 Homepage:      https://github.com/haskell/stylish-haskell
 License:       BSD-3-Clause
@@ -37,7 +37,7 @@
 
   Build-depends:
     aeson             >= 0.6    && < 2.3,
-    base              >= 4.8    && < 5,
+    base              >= 4.19    && < 5,
     bytestring        >= 0.9    && < 0.13,
     Cabal             >= 3.10   && < 4.0,
     containers        >= 0.3    && < 0.9,
@@ -59,17 +59,17 @@
   -- and we have a new enough GHC. Note that
   -- this will only work if the user's
   -- compiler is of the matching major version!
-  if !flag(ghc-lib) && impl(ghc >= 9.8) && impl(ghc < 9.11)
+  if !flag(ghc-lib) && impl(ghc >= 9.8) && impl(ghc < 9.13)
     Build-depends:
-      ghc >= 9.10 && < 9.11,
+      ghc >= 9.12 && < 9.13,
       ghc-boot,
       ghc-boot-th
   else
     Build-depends:
-      ghc-lib-parser >= 9.10 && < 9.11
+      ghc-lib-parser >= 9.12 && < 9.13
 
   Build-depends:
-    ghc-lib-parser-ex >= 9.10 && < 9.11
+    ghc-lib-parser-ex >= 9.12 && < 9.13
 
 Library
   Import:         depends