diff --git a/lib/classes/task/file_temp_cleanup_task.php b/lib/classes/task/file_temp_cleanup_task.php
index 0b0253ac3b2..7166872e660 100644
--- a/lib/classes/task/file_temp_cleanup_task.php
+++ b/lib/classes/task/file_temp_cleanup_task.php
@@ -38,13 +38,13 @@ class file_temp_cleanup_task extends scheduled_task {
     }
 
     /**
-     * Do the job.
-     * Throw exceptions on errors (the job will be retried).
+     * Do the job, given the target directory.
+     *
+     * @param string $tmpdir The directory hosting the candidate stale temp files.
      */
-    public function execute() {
+    protected function execute_on($tmpdir) {
         global $CFG;
 
-        $tmpdir = $CFG->tempdir;
         // Default to last weeks time.
         $time = time() - ($CFG->tempdatafoldercleanup * 3600);
 
@@ -96,4 +96,23 @@ class file_temp_cleanup_task extends scheduled_task {
         }
     }
 
+    /**
+     * Do the job.
+     * Throw exceptions on errors (the job will be retried).
+     */
+    public function execute() {
+        global $CFG;
+
+        // The directories hosting the candidate stale temp files eventually are $CFG->tempdir and $CFG->backuptempdir.
+
+        // Do the job on each of the directories above.
+        // Let's start with $CFG->tempdir.
+        $this->execute_on($CFG->tempdir);
+
+        // Run on $CFG->backuptempdir too, if different from the default one, '$CFG->tempdir/backup'.
+        if (realpath(dirname($CFG->backuptempdir)) !== $CFG->tempdir) {
+            // The $CFG->backuptempdir setting is different from the default '$CFG->tempdir/backup'.
+            $this->execute_on($CFG->backuptempdir);
+        }
+    }
 }