diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 606156946e4cdcf5c33f6ba1b6c481990e745ffa..1f29c246dafdbed44e20b5720221810f0642ff81 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -1391,10 +1391,11 @@ function drupal_unpack($obj, $field = 'data') {
  * The t() function serves two purposes. First, at run-time it translates
  * user-visible text into the appropriate language. Second, various mechanisms
  * that figure out what text needs to be translated work off t() -- the text
- * inside t() calls is added to the database of strings to be translated. So,
- * to enable a fully-translatable site, it is important that all human-readable
- * text that will be displayed on the site or sent to a user is passed through
- * the t() function, or a related function. See the
+ * inside t() calls is added to the database of strings to be translated.
+ * These strings are expected to be in English, so the first argument should
+ * always be in English. To enable a fully-translatable site, it is important
+ * that all human-readable text that will be displayed on the site or sent to
+ * a user is passed through the t() function, or a related function. See the
  * @link http://drupal.org/node/322729 Localization API @endlink pages for
  * more information, including recommendations on how to break up or not
  * break up strings for translation.