diff --git a/classes/modules/turnitin_quiz.class.php b/classes/modules/turnitin_quiz.class.php
index 9746bffc..3802630d 100644
--- a/classes/modules/turnitin_quiz.class.php
+++ b/classes/modules/turnitin_quiz.class.php
@@ -150,8 +150,13 @@ public function update_mark($attemptid, $identifier, $userid, $grade, $quizgrade
         global $DB;
 
         $transaction = $DB->start_delegated_transaction();
+        if (class_exists('\mod_quiz\quiz_attempt')) {
+            $quizattemptclass = '\mod_quiz\quiz_attempt';
+        } else {
+            $quizattemptclass = 'quiz_attempt';
+        }
 
-        $attempt = \mod_quiz\quiz_attempt::create($attemptid);
+        $attempt = $quizattemptclass::create($attemptid);
         $quba = question_engine::load_questions_usage_by_activity($attempt->get_uniqueid());
 
         // Loop through each question slot.
@@ -177,7 +182,13 @@ public function update_mark($attemptid, $identifier, $userid, $grade, $quizgrade
         $update->sumgrades = $quba->get_total_mark();
         $DB->update_record('quiz_attempts', $update);
 
-        $attempt->get_quizobj()->get_grade_calculator()->recompute_final_grade($userid);
+        if (class_exists('\mod_quiz\grade_calculator')) {
+            // Support Moodle 4.3+.
+            $attempt->get_quizobj()->get_grade_calculator()->recompute_final_grade($userid);
+        } else {
+            // Support older Moodle versions.
+            quiz_save_best_grade($attempt->get_quiz(), $userid);
+        }
 
         $transaction->allow_commit();
     }
diff --git a/tests/modules/turnitin_assign_test.php b/tests/modules/turnitin_assign_test.php
index ca8697d1..0f43aacd 100644
--- a/tests/modules/turnitin_assign_test.php
+++ b/tests/modules/turnitin_assign_test.php
@@ -46,6 +46,12 @@ final class turnitin_assign_test extends \advanced_testcase {
      */
     public $assign;
 
+    /** @var stdClass created in setUp. */
+    protected $course;
+
+    /** @var stdClass created in setUp. */
+    protected $assign;
+
     /**
      * Create a course and assignment module instance
      */
diff --git a/tests/modules/turnitin_forum_test.php b/tests/modules/turnitin_forum_test.php
index d7071ce4..42e3eada 100644
--- a/tests/modules/turnitin_forum_test.php
+++ b/tests/modules/turnitin_forum_test.php
@@ -51,6 +51,15 @@ final class turnitin_forum_test extends \advanced_testcase {
      */
     public $post;
 
+    /** @var stdClass created in setUp. */
+    protected $forum;
+
+    /** @var stdClass created in setUp. */
+    protected $discussion;
+
+    /** @var stdClass created in setUp. */
+    protected $post;
+
     /**
      * Create a course and forum module instance
      */
diff --git a/tests/modules/turnitin_quiz_test.php b/tests/modules/turnitin_quiz_test.php
index a1f6967f..39a435d0 100644
--- a/tests/modules/turnitin_quiz_test.php
+++ b/tests/modules/turnitin_quiz_test.php
@@ -58,8 +58,16 @@ public function test_update_mark(): void {
             'layout' => '1,0',
         ]);
 
-        $quizobj = \mod_quiz\quiz_settings::create($quiz->id, $user->id);
-        $quba = \question_engine::make_questions_usage_by_activity('mod_quiz', $quizobj->get_context());
+        if (class_exists('\mod_quiz\quiz_settings')) {
+            $quizsettingsclass = '\mod_quiz\quiz_settings';
+            $quizattemptclass = '\mod_quiz\quiz_attempt';
+        } else {
+            $quizsettingsclass = 'quiz';
+            $quizattemptclass = 'quiz_attempt';
+        }
+
+        $quizobj = $quizsettingsclass::create($quiz->id, $user->id);
+        $quba = question_engine::make_questions_usage_by_activity('mod_quiz', $quizobj->get_context());
         $quba->set_preferred_behaviour($quizobj->get_quiz()->preferredbehaviour);
 
         $questiongenerator = $this->getDataGenerator()->get_plugin_generator('core_question');
@@ -72,11 +80,11 @@ public function test_update_mark(): void {
         $attempt = quiz_create_attempt($quizobj, 1, false, $timenow, false, $user->id);
         quiz_start_new_attempt($quizobj, $quba, $attempt, 1, $timenow);
         quiz_attempt_save_started($quizobj, $quba, $attempt);
-        $attemptobj = \mod_quiz\quiz_attempt::create($attempt->id);
+        $attemptobj = $quizattemptclass::create($attempt->id);
         $attemptobj->process_finish($timenow, false);
 
         // Expect no marks or grade for the attempt yet.
-        $attemptobj = \mod_quiz\quiz_attempt::create($attempt->id);
+        $attemptobj = $quizattemptclass::create($attempt->id);
         $this->assertEquals(0.0, $attemptobj->get_sum_marks());
         $grade = quiz_get_best_grade($quiz, $user->id);
         $this->assertEquals(0.0, $grade);
@@ -89,7 +97,7 @@ public function test_update_mark(): void {
         $tiiquiz->update_mark($attempt->id, $identifier, $user->id, 75, $quiz->grade);
 
         // Reload the attempt and check the total marks and grade are as we expect it.
-        $attemptobj = \mod_quiz\quiz_attempt::create($attempt->id);
+        $attemptobj = $quizattemptclass::create($attempt->id);
         $this->assertEquals(0.75, $attemptobj->get_sum_marks());
         $grade = quiz_get_best_grade($quiz, $user->id);
         $this->assertEquals(75.0, $grade);