diff --git a/lang/en/quiz.php b/lang/en/quiz.php
index <HASH>..<HASH> 100644
--- a/lang/en/quiz.php
+++ b/lang/en/quiz.php
@@ -273,7 +273,7 @@ $string['penalty'] = 'Penalty';
 $string['penaltyfactor'] = 'Penalty factor';
 $string['penaltyscheme'] = 'Apply penalties';
 $string['percentcorrect'] = 'Percent Correct';
-$string['popup'] = 'Show quiz in a \"secure\" window';
+$string['popup'] = 'Show quiz in a &quot;secure&quot; window';
 $string['popupnotice'] = 'Students will see this quiz in a secure window';
 $string['preview'] = 'Preview';
 $string['previewquestion'] = 'Preview question';
These quotes were going into (quoted) HTML attributes and breaking XHTML.