diff --git a/ext/js/language/language-descriptors.js b/ext/js/language/language-descriptors.js
index 85976621d..48d25b1d1 100644
--- a/ext/js/language/language-descriptors.js
+++ b/ext/js/language/language-descriptors.js
@@ -400,6 +400,13 @@ const languageDescriptors = [
             normalizeDiacritics,
         },
     },
+    {
+        iso: 'cy',
+        iso639_3: 'cym',
+        name: 'Welsh',
+        exampleText: 'ddarllen',
+        textPreprocessors: capitalizationPreprocessors,
+    },
     {
         iso: 'yi',
         iso639_3: 'yid',
diff --git a/types/ext/language-descriptors.d.ts b/types/ext/language-descriptors.d.ts
index 82c46acb3..9a6aa30f7 100644
--- a/types/ext/language-descriptors.d.ts
+++ b/types/ext/language-descriptors.d.ts
@@ -212,6 +212,9 @@ type AllTextProcessors = {
             normalizeDiacritics: TextProcessor<'old' | 'new' | 'off'>;
         };
     };
+    cy: {
+        pre: CapitalizationPreprocessors;
+    };
     yi: {
         pre: {
             combineYiddishLigatures: TextProcessor<boolean>;