diff --git a/mod/lti/service/gradebookservices/classes/local/service/gradebookservices.php b/mod/lti/service/gradebookservices/classes/local/service/gradebookservices.php
index caa437aca35..e51e41f2355 100644
--- a/mod/lti/service/gradebookservices/classes/local/service/gradebookservices.php
+++ b/mod/lti/service/gradebookservices/classes/local/service/gradebookservices.php
@@ -721,7 +721,7 @@ class gradebookservices extends service_base {
             $gradebookroles = explode(',', $CFG->gradebookroles);
             foreach ($roles as $role) {
                 foreach ($gradebookroles as $gradebookrole) {
-                    if ($role->roleid = $gradebookrole) {
+                    if ($role->roleid === $gradebookrole) {
                         $gradableuser = true;
                     }
                 }
diff --git a/mod/lti/service/gradebookservices/tests/gradebookservices_test.php b/mod/lti/service/gradebookservices/tests/gradebookservices_test.php
index da713e9a526..765a67b51ba 100644
--- a/mod/lti/service/gradebookservices/tests/gradebookservices_test.php
+++ b/mod/lti/service/gradebookservices/tests/gradebookservices_test.php
@@ -150,6 +150,23 @@ class mod_lti_gradebookservices_testcase extends advanced_testcase {
         $this->assertFalse(array_key_exists('$LineItem.url', $params));
     }
 
+    /**
+     * Test if a user can be graded in a course.
+     */
+    public function test_is_user_gradable_in_course() {
+        $this->resetAfterTest();
+
+        $generator = $this->getDataGenerator();
+        $course = $generator->create_course();
+        $user1 = $generator->create_user();
+        $user2 = $generator->create_user();
+        $generator->enrol_user($user1->id, $course->id, 'student');
+        $generator->enrol_user($user2->id, $course->id, 'editingteacher');
+
+        $this->assertTrue(gradebookservices::is_user_gradable_in_course($course->id, $user1->id));
+        $this->assertFalse(gradebookservices::is_user_gradable_in_course($course->id, $user2->id));
+    }
+
     /**
      * Asserts a matching gradebookservices record exist with the matching tag and resourceid.
      *