diff --git a/question/type/calculated/tests/variablesubstituter_test.php b/question/type/calculated/tests/variablesubstituter_test.php
index f2513371934..f9be863b591 100644
--- a/question/type/calculated/tests/variablesubstituter_test.php
+++ b/question/type/calculated/tests/variablesubstituter_test.php
@@ -28,6 +28,7 @@ defined('MOODLE_INTERNAL') || die();
 
 global $CFG;
 require_once($CFG->dirroot . '/question/type/calculated/question.php');
+require_once($CFG->dirroot . '/question/type/calculated/questiontype.php');
 
 
 /**