diff --git a/tool_translations_config.py b/tool_translations_config.py
index 0710a1f..1e4abba 100644
--- a/tool_translations_config.py
+++ b/tool_translations_config.py
@@ -1,7 +1,18 @@
+import toolforge_i18n
 from toolforge_i18n import (
     TranslationsConfig,  # pyright: ignore[reportPrivateImportUsage]
 )
 
+
+def language_code_to_babel(code: str) -> str:
+    mediawiki_to_babel = {
+        "pms": "it",  # 2026-09-01: Piedmontese, not supported
+    }
+    if code in mediawiki_to_babel:
+        return mediawiki_to_babel[code]
+    return toolforge_i18n.language_code_to_babel(code)  # pyright: ignore[reportPrivateImportUsage]
+
+
 config = TranslationsConfig(
     variables={
         "login-error": ["error_text"],
@@ -48,4 +59,5 @@ config = TranslationsConfig(
         "strong": set(),
         "em": set(),
     },
+    language_code_to_babel=language_code_to_babel,
 )