diff --git a/mod/quiz/report/overview/report.php b/mod/quiz/report/overview/report.php
index 0ef2a32f7e5..7a9b5e14577 100644
--- a/mod/quiz/report/overview/report.php
+++ b/mod/quiz/report/overview/report.php
@@ -202,7 +202,7 @@ class quiz_overview_report extends quiz_default_report {
         if (!$nostudents || ($attemptsmode == QUIZ_REPORT_ATTEMPTS_ALL)) {
 
             // Construct the SQL
-            $fields = $DB->sql_concat('u.id', '\'#\'', 'COALESCE(qa.attempt, \'0\')').' AS uniqueid, ';
+            $fields = $DB->sql_concat('u.id', '\'#\'', 'COALESCE(qa.attempt, 0)').' AS uniqueid, ';
             if ($qmsubselect) {
                 $fields .=
                     "(CASE " .
diff --git a/mod/quiz/report/responses/report.php b/mod/quiz/report/responses/report.php
index b73ccfd7517..01662ff6a6b 100644
--- a/mod/quiz/report/responses/report.php
+++ b/mod/quiz/report/responses/report.php
@@ -185,7 +185,7 @@ class quiz_responses_report extends quiz_default_report {
             $hasfeedback = quiz_has_feedback($quiz);
 
             // Construct the SQL
-            $fields = $DB->sql_concat('u.id', '\'#\'', 'COALESCE(qa.attempt, \'0\')').' AS concattedid, ';
+            $fields = $DB->sql_concat('u.id', '\'#\'', 'COALESCE(qa.attempt, 0)').' AS concattedid, ';
             if ($qmsubselect) {
                 $fields .=
                     "(CASE " .