diff --git a/cabal-docspec/Changelog.md b/cabal-docspec/Changelog.md
index 4f2e0cc..6e54396 100644
--- a/cabal-docspec/Changelog.md
+++ b/cabal-docspec/Changelog.md
@@ -1,3 +1,7 @@
+# 0.0.0.202312dd
+
+- Pass `default-language` flag to GHC
+
 # 0.0.0.20230406
 
 - Change failing docspec output to be proper diff.
diff --git a/cabal-docspec/src/CabalDocspec/Opts.hs b/cabal-docspec/src/CabalDocspec/Opts.hs
index e2ed132..ba107c6 100644
--- a/cabal-docspec/src/CabalDocspec/Opts.hs
+++ b/cabal-docspec/src/CabalDocspec/Opts.hs
@@ -84,8 +84,14 @@ data Phase
 -- TODO: take tracer
 dynOptsFromBuildInfo :: TracerPeu r Tr -> C.BuildInfo -> Peu r (DynOpts -> DynOpts)
 dynOptsFromBuildInfo tracer bi = do
+    let lang = case C.defaultLanguage bi of
+            Nothing -> id
+            Just l  -> \dynOpts -> dynOpts
+                { optExts = prettyShow l : optExts dynOpts
+                }
+
     endos <- for customFields (uncurry parse)
-    return $ \x -> foldl' (&) x endos
+    return $ \x -> foldl' (&) x (lang : endos)
   where
     customFields = C.customFieldsBI bi