diff --git a/Cabal-syntax/src/Language/Haskell/Extension.hs b/Cabal-syntax/src/Language/Haskell/Extension.hs
index d5fb797eea6..7ba005d84dd 100644
--- a/Cabal-syntax/src/Language/Haskell/Extension.hs
+++ b/Cabal-syntax/src/Language/Haskell/Extension.hs
@@ -16,6 +16,7 @@
 module Language.Haskell.Extension
   ( Language (..)
   , knownLanguages
+  , defaultDefLang
   , classifyLanguage
   , Extension (..)
   , KnownExtension (..)
@@ -67,6 +68,10 @@ instance NFData Language where rnf = genericRnf
 knownLanguages :: [Language]
 knownLanguages = [Haskell98, Haskell2010, GHC2021]
 
+-- | When @default-language@ is missing, 'Haskell98' is the choice.
+defaultDefLang :: Language
+defaultDefLang = Haskell98
+
 instance Pretty Language where
   pretty (UnknownLanguage other) = Disp.text other
   pretty other = Disp.text (show other)
diff --git a/Cabal/src/Distribution/Simple/GHC/Internal.hs b/Cabal/src/Distribution/Simple/GHC/Internal.hs
index 0574a868ba7..09d05c58851 100644
--- a/Cabal/src/Distribution/Simple/GHC/Internal.hs
+++ b/Cabal/src/Distribution/Simple/GHC/Internal.hs
@@ -583,7 +583,7 @@ componentGhcOptions verbosity lbi bi clbi odir =
         , ghcOptDebugInfo = toFlag (withDebugInfo lbi)
         , ghcOptExtra = hcOptions GHC bi
         , ghcOptExtraPath = toNubListR $ exe_paths
-        , ghcOptLanguage = toFlag (fromMaybe Haskell98 (defaultLanguage bi))
+        , ghcOptLanguage = toFlag (fromMaybe defaultDefLang (defaultLanguage bi))
         , -- Unsupported extensions have already been checked by configure
           ghcOptExtensions = toNubListR $ usedExtensions bi
         , ghcOptExtensionMap = Map.fromList . compilerExtensions $ (compiler lbi)
diff --git a/Cabal/src/Distribution/Simple/HaskellSuite.hs b/Cabal/src/Distribution/Simple/HaskellSuite.hs
index d59c4703fc4..4a35de13ad8 100644
--- a/Cabal/src/Distribution/Simple/HaskellSuite.hs
+++ b/Cabal/src/Distribution/Simple/HaskellSuite.hs
@@ -181,7 +181,7 @@ buildLib verbosity pkg_descr lbi lib clbi = do
       bi = libBuildInfo lib
       srcDirs = map getSymbolicPath (hsSourceDirs bi) ++ [odir]
       dbStack = withPackageDB lbi
-      language = fromMaybe Haskell98 (defaultLanguage bi)
+      language = fromMaybe defaultDefLang (defaultLanguage bi)
       progdb = withPrograms lbi
       pkgid = packageId pkg_descr
 
diff --git a/cabal-install/src/Distribution/Client/CmdRepl.hs b/cabal-install/src/Distribution/Client/CmdRepl.hs
index e243eb82974..3c72f989cc1 100644
--- a/cabal-install/src/Distribution/Client/CmdRepl.hs
+++ b/cabal-install/src/Distribution/Client/CmdRepl.hs
@@ -154,7 +154,7 @@ import Distribution.Verbosity
   , normal
   )
 import Language.Haskell.Extension
-  ( Language (..)
+  ( defaultDefLang
   )
 
 import Control.Monad (mapM)
@@ -304,7 +304,7 @@ replAction flags@NixStyleFlags{extraFlags = r@ReplFlags{..}, ..} targetStrings g
           lBuildInfo =
             emptyBuildInfo
               { targetBuildDepends = [baseDep]
-              , defaultLanguage = Just Haskell2010
+              , defaultLanguage = Just defaultDefLang
               }
           baseDep = Dependency "base" anyVersion mainLibSet
 
diff --git a/cabal-install/src/Distribution/Client/ScriptUtils.hs b/cabal-install/src/Distribution/Client/ScriptUtils.hs
index 1793f6aa07d..f88b767a0cf 100644
--- a/cabal-install/src/Distribution/Client/ScriptUtils.hs
+++ b/cabal-install/src/Distribution/Client/ScriptUtils.hs
@@ -179,7 +179,7 @@ import Distribution.Verbosity
   ( normal
   )
 import Language.Haskell.Extension
-  ( Language (..)
+  ( defaultDefLang
   )
 
 import Control.Concurrent.MVar
@@ -377,7 +377,7 @@ withContextAndSelectors noTargets kind flags@NixStyleFlags{..} targetStrings glo
 
               executable' =
                 executable
-                  & L.buildInfo . L.defaultLanguage %~ maybe (Just Haskell2010) Just
+                  & L.buildInfo . L.defaultLanguage %~ maybe (Just defaultDefLang) Just
                   & L.buildInfo . L.options %~ fmap (setExePath exePathRel)
 
           createDirectoryIfMissingVerbose verbosity True (takeDirectory exePath)
diff --git a/doc/cabal-package-description-file.rst b/doc/cabal-package-description-file.rst
index 8e5e59db1cf..e87875bcf64 100644
--- a/doc/cabal-package-description-file.rst
+++ b/doc/cabal-package-description-file.rst
@@ -1732,7 +1732,7 @@ system-dependent values for these fields.
 
     -  ``GHC2021`` (only available for GHC version newer than ``9.2``)
     -  ``Haskell2010``
-    -  ``Haskell98``
+    -  ``Haskell98`` (default)
 
 .. pkg-field:: other-languages: identifier
    :since: 1.12