diff --git a/TODO.md b/TODO.md
index 897264e..ca38902 100644
--- a/TODO.md
+++ b/TODO.md
@@ -4,3 +4,4 @@
 - [x] Fix `ShareLink::setPassword()`: also encrypt and store plain-text password, matching `create()` behavior
 - [x] Audit: confirm all remaining credential comparison sites use constant-time `hash_equals` or `password_verify`
 - [x] Fix `.gitignore`: anchor `vendor/` to root (`/vendor/`) so `app/public/assets/js/vendor/` (htmx, OverType, FilePond) is tracked
+- [x] Fix migration `025_lowercase_languages.sql`: deduplicate languages before LOWER() to avoid UNIQUE constraint violation (`Néerlandais`/`néerlandais`)
diff --git a/app/migrations/applied/025_lowercase_languages.sql b/app/migrations/applied/025_lowercase_languages.sql
index 320dc33..b0b10f5 100644
--- a/app/migrations/applied/025_lowercase_languages.sql
+++ b/app/migrations/applied/025_lowercase_languages.sql
@@ -1,6 +1,14 @@
 -- 025_lowercase_languages.sql
 -- Normalise les noms de langues en minuscules et recrée la vue avec ucfirst.
 
+-- Supprimer les doublons (même nom après LOWER) en gardant l'id le plus petit
+DELETE FROM languages
+WHERE id NOT IN (
+    SELECT MIN(id)
+    FROM languages
+    GROUP BY LOWER(name)
+);
+
 -- Normaliser les langues existantes
 UPDATE languages SET name = LOWER(name);