diff --git a/mod/quiz/report/attemptsreport.php b/mod/quiz/report/attemptsreport.php
index f26b2ec7071..6c7ab35ea9e 100644
--- a/mod/quiz/report/attemptsreport.php
+++ b/mod/quiz/report/attemptsreport.php
@@ -360,7 +360,7 @@ abstract class quiz_attempt_report extends quiz_default_report {
                 // Ensure the attempt exists, and belongs to this quiz. If not skip.
                 continue;
             }
-            if ($allowed && !array_key_exists($attempt->userid, $allowed)) {
+            if ($allowed && !in_array($attempt->userid, $allowed)) {
                 // Ensure the attempt belongs to a student included in the report. If not skip.
                 continue;
             }