diff --git a/classes/search/SubmissionSearch.php b/classes/search/SubmissionSearch.php
index ed3ba0e3411..fcec53a92e4 100644
--- a/classes/search/SubmissionSearch.php
+++ b/classes/search/SubmissionSearch.php
@@ -236,7 +236,7 @@ protected function _getMergedPhraseResults($context, &$phrase, $type, $published
      * Keywords are supplied in an array of the following format:
      * $keywords[SUBMISSION_SEARCH_AUTHOR] = array('John', 'Doe');
      * $keywords[SUBMISSION_SEARCH_...] = array(...);
-     * $keywords[null] = array('Matches', 'All', 'Fields');
+     * $keywords[''] = array('Matches', 'All', 'Fields');
      *
      * @param Request $request
      * @param Context $context The context to search