diff --git a/.github/CONTRIBUTING.md b/.github/CONTRIBUTING.md
index 205df7b2..2e4e4283 100644
--- a/.github/CONTRIBUTING.md
+++ b/.github/CONTRIBUTING.md
@@ -24,6 +24,9 @@ If not, then provide details describing which page the feature will effect, e.g.
 ## Adding translations
 
 You can help us translate the extension on [Transifex](https://www.transifex.com/github-7/Stylus).
+Only the languages supported by the web store are allowed:
+https://developer.chrome.com/docs/webstore/i18n/#localeTable
+
 
 ## Pull requests