diff --git a/mod/forum/backup/moodle2/backup_forum_activity_task.class.php b/mod/forum/backup/moodle2/backup_forum_activity_task.class.php
index cbff0760307..1fe837b961a 100644
--- a/mod/forum/backup/moodle2/backup_forum_activity_task.class.php
+++ b/mod/forum/backup/moodle2/backup_forum_activity_task.class.php
@@ -71,7 +71,7 @@ class backup_forum_activity_task extends backup_activity_task {
         $content= preg_replace($search, '$@FORUMVIEWBYF*$2@$', $content);
 
         // Link to forum discussion with parent syntax
-        $search="/(".$base."\/mod\/forum\/discuss.php\?d\=)([0-9]+)\&parent\=([0-9]+)/";
+        $search = "/(".$base."\/mod\/forum\/discuss.php\?d\=)([0-9]+)(?:\&|\&)parent\=([0-9]+)/";
         $content= preg_replace($search, '$@FORUMDISCUSSIONVIEWPARENT*$2*$3@$', $content);
 
         // Link to forum discussion with relative syntax
diff --git a/mod/forum/tests/backup_forum_activity_test.php b/mod/forum/tests/backup_forum_activity_test.php
new file mode 100644
index 00000000000..0aad303caf6
--- /dev/null
+++ b/mod/forum/tests/backup_forum_activity_test.php
@@ -0,0 +1,118 @@
+<?php
+// This file is part of Moodle - http://moodle.org/
+//
+// Moodle is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// Moodle is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
+
+/**
+ * Tests for mod_forum_backup_forum_activity_task.
+ *
+ * @package    mod_forum
+ * @category   test
+ * @copyright  2016 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+
+defined('MOODLE_INTERNAL') || die();
+
+global $CFG;
+require_once($CFG->dirroot . '/backup/util/plan/backup_structure_step.class.php');
+require_once($CFG->dirroot . '/backup/moodle2/backup_stepslib.php');
+require_once($CFG->dirroot . '/backup/moodle2/backup_activity_task.class.php');
+require_once($CFG->dirroot . '/mod/forum/backup/moodle2/backup_forum_activity_task.class.php');
+
+/**
+ * Tests for mod_forum_backup_forum_activity_task.
+ *
+ * @package    mod_forum
+ * @category   test
+ * @copyright  2016 Andrew Nicols <andrew@nicols.co.uk>
+ * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class mod_forum_backup_forum_activity_task_testcase extends advanced_testcase {
+
+    /**
+     * Test the encoding of forum content links.
+     *
+     * @param string $content       The incoming content
+     * @param string $expectation   The expected result
+     *
+     * @dataProvider encode_content_links_provider
+     */
+    public function test_encode_content_links($content, $expectation) {
+        $this->assertEquals($expectation, backup_forum_activity_task::encode_content_links($content));
+    }
+
+    public function encode_content_links_provider() {
+        global $CFG;
+        $altwwwroot = 'http://invalid.example.com/';
+        return [
+            'Link to the list of forums for current wwwroot' => [
+                sprintf('%s/mod/forum/index.php?id=42', $CFG->wwwroot),
+                '$@FORUMINDEX*42@$',
+            ],
+            'Link to forum view by moduleid for current wwwroot' => [
+                sprintf('%s/mod/forum/view.php?id=29', $CFG->wwwroot),
+                '$@FORUMVIEWBYID*29@$',
+            ],
+            'Link to forum view by forumid for current wwwroot' => [
+                sprintf('%s/mod/forum/view.php?f=31', $CFG->wwwroot),
+                '$@FORUMVIEWBYF*31@$',
+            ],
+            'Link to forum discussion with parent syntax for current wwwroot' => [
+                sprintf('%s/mod/forum/discuss.php?d=26&parent=99', $CFG->wwwroot),
+                '$@FORUMDISCUSSIONVIEWPARENT*26*99@$',
+            ],
+            'Link to forum discussion with parent syntax for current wwwroot encoded' => [
+                sprintf('%s/mod/forum/discuss.php?d=26&amp;parent=99', $CFG->wwwroot),
+                '$@FORUMDISCUSSIONVIEWPARENT*26*99@$',
+            ],
+            'Link to forum discussion with relative syntax for current wwwroot' => [
+                sprintf('%s/mod/forum/discuss.php?d=1040#9930', $CFG->wwwroot),
+                '$@FORUMDISCUSSIONVIEWINSIDE*1040*9930@$',
+            ],
+            'Link to forum discussion by discussionid for current wwwroot' => [
+                sprintf('%s/mod/forum/discuss.php?d=9304', $CFG->wwwroot),
+                '$@FORUMDISCUSSIONVIEW*9304@$',
+            ],
+            'Link to the list of forums for other wwwroot' => [
+                sprintf('%s/mod/forum/index.php?id=42', $altwwwroot),
+                sprintf('%s/mod/forum/index.php?id=42', $altwwwroot),
+            ],
+            'Link to forum view by moduleid for other wwwroot' => [
+                sprintf('%s/mod/forum/view.php?id=29', $altwwwroot),
+                sprintf('%s/mod/forum/view.php?id=29', $altwwwroot),
+            ],
+            'Link to forum view by forumid for other wwwroot' => [
+                sprintf('%s/mod/forum/view.php?f=31', $altwwwroot),
+                sprintf('%s/mod/forum/view.php?f=31', $altwwwroot),
+            ],
+            'Link to forum discussion with parent syntax for other wwwroot' => [
+                sprintf('%s/mod/forum/discuss.php?d=26&parent=99', $altwwwroot),
+                sprintf('%s/mod/forum/discuss.php?d=26&parent=99', $altwwwroot),
+            ],
+            'Link to forum discussion with parent syntax for other wwwroot encoded' => [
+                sprintf('%s/mod/forum/discuss.php?d=26&amp;parent=99', $altwwwroot),
+                sprintf('%s/mod/forum/discuss.php?d=26&amp;parent=99', $altwwwroot),
+            ],
+            'Link to forum discussion with relative syntax for other wwwroot' => [
+                sprintf('%s/mod/forum/discuss.php?d=1040#9930', $altwwwroot),
+                sprintf('%s/mod/forum/discuss.php?d=1040#9930', $altwwwroot),
+            ],
+            'Link to forum discussion by discussionid for other wwwroot' => [
+                sprintf('%s/mod/forum/discuss.php?d=9304', $altwwwroot),
+                sprintf('%s/mod/forum/discuss.php?d=9304', $altwwwroot),
+            ],
+        ];
+    }
+}