diff --git a/config.sample/flat_auth_pw b/config.sample/flat_auth_pw
index cdae7f7..fcf3b3c 100644
--- a/config.sample/flat_auth_pw
+++ b/config.sample/flat_auth_pw
@@ -1,3 +1,4 @@
+# used by plugins/auth/auth_flat_file
 # example entries
 good@example.com:good_pass
 bad@example.com:bad_pass