diff --git a/.env.test b/.env.test
index 4cd76d6f0a..6d4d943414 100644
--- a/.env.test
+++ b/.env.test
@@ -1,7 +1,8 @@
 # ENV vars for the test environment
 # Override locally with `.env.test.local`
 
-# Locale for translation.
+# Locale for translation. Using a locale other than `en` tests the
+# successful fallback to `en`.
 LOCALE="en_TST"
 
 OFN_REDIS_JOBS_URL="redis://localhost:6379/2"