diff --git a/backup/util/plan/backup_structure_step.class.php b/backup/util/plan/backup_structure_step.class.php
index 5d8cb557573..e18ada4b049 100644
--- a/backup/util/plan/backup_structure_step.class.php
+++ b/backup/util/plan/backup_structure_step.class.php
@@ -183,6 +183,10 @@ abstract class backup_structure_step extends backup_step {
      * @return void
      */
     protected function add_subplugin_structure($subplugintype, $element, $multiple, $plugintype = null, $pluginname = null) {
+        global $CFG;
+        // This global declaration is required, because where we do require_once($backupfile);
+        // That file may in turn try to do require_once($CFG->dirroot ...).
+        // That worked in the past, we should keep it working.
 
         // Verify if this is a BC call for an activity backup. See NOTE above for this special case.
         if ($plugintype === null and $pluginname === null) {
diff --git a/backup/util/plan/restore_structure_step.class.php b/backup/util/plan/restore_structure_step.class.php
index de7b0029c3a..b59ac82f479 100644
--- a/backup/util/plan/restore_structure_step.class.php
+++ b/backup/util/plan/restore_structure_step.class.php
@@ -313,6 +313,10 @@ abstract class restore_structure_step extends restore_step {
      * @return void
      */
     protected function add_subplugin_structure($subplugintype, $element, $plugintype = null, $pluginname = null) {
+        global $CFG;
+        // This global declaration is required, because where we do require_once($backupfile);
+        // That file may in turn try to do require_once($CFG->dirroot ...).
+        // That worked in the past, we should keep it working.
 
         // Verify if this is a BC call for an activity restore. See NOTE above for this special case.
         if ($plugintype === null and $pluginname === null) {