diff --git a/mod/wiki/backup/moodle2/restore_wiki_stepslib.php b/mod/wiki/backup/moodle2/restore_wiki_stepslib.php
index 4a93bcffc6d..1a2facd4a58 100644
--- a/mod/wiki/backup/moodle2/restore_wiki_stepslib.php
+++ b/mod/wiki/backup/moodle2/restore_wiki_stepslib.php
@@ -61,6 +61,7 @@ class restore_wiki_activity_structure_step extends restore_activity_structure_st
         // See MDL-9367.
         $data->editbegin = $this->apply_date_offset($data->editbegin);
         $data->editend = $this->apply_date_offset($data->editend);
+        $data->defaultformat = clean_param($data->defaultformat, PARAM_ALPHA);
 
         // insert the wiki record
         $newitemid = $DB->insert_record('wiki', $data);
@@ -120,7 +121,7 @@ class restore_wiki_activity_structure_step extends restore_activity_structure_st
         $oldid = $data->id;
         $data->pageid = $this->get_new_parentid('wiki_page');
         $data->userid = $this->get_mappingid('user', $data->userid);
-
+        $data->contentformat = clean_param($data->contentformat, PARAM_ALPHA);
         $newitemid = $DB->insert_record('wiki_versions', $data);
         $this->set_mapping('wiki_version', $oldid, $newitemid);
     }
diff --git a/mod/wiki/parser/parser.php b/mod/wiki/parser/parser.php
index a8bd62f17e6..1865a2f590b 100644
--- a/mod/wiki/parser/parser.php
+++ b/mod/wiki/parser/parser.php
@@ -44,16 +44,20 @@ defined('MOODLE_INTERNAL') || die();
  * @package mod_wiki
  */
 class wiki_parser_proxy {
-    private static $parsers = array();
-    private static $basepath = "";
-
-    public static function parse(&$string, $type, $options = array()) {
-
-        if (empty(self::$basepath)) {
-            global $CFG;
-            self::$basepath = $CFG->dirroot . '/mod/wiki/parser/';
-        }
+    /**
+     * @var array $parsers Array of parser instances
+     */
+    private static $parsers = [];
 
+    /**
+     * Parse a string using a specific parser
+     *
+     * @param string $string The string to parse
+     * @param string $type The parser type
+     * @param array $options The parser options
+     * @return mixed The parsed string or false if the parser type is not found
+     */
+    public static function parse(&$string, $type, $options = []) {
         $type = strtolower($type);
         self::$parsers[$type] = null; // Reset the current parser because it may have other options.
         if (self::create_parser_instance($type)) {
@@ -86,8 +90,14 @@ class wiki_parser_proxy {
     }
 
     private static function create_parser_instance($type) {
+        global $CFG;
+        $type = clean_param($type, PARAM_ALPHA);
         if (empty(self::$parsers[$type])) {
-            include_once(self::$basepath . "markups/$type.php");
+            $path = "$CFG->dirroot/mod/wiki/parser/markups/$type.php";
+            if (!file_exists($path)) {
+                throw new moodle_exception("Parser type $type not found");
+            }
+            include_once($path);
             $class = strtolower($type) . "_parser";
             if (class_exists($class)) {
                 self::$parsers[$type] = new $class;
diff --git a/mod/wiki/tests/backup/restore_format_test.php b/mod/wiki/tests/backup/restore_format_test.php
new file mode 100644
index 00000000000..0c4ff22f62a
--- /dev/null
+++ b/mod/wiki/tests/backup/restore_format_test.php
@@ -0,0 +1,80 @@
+<?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/>.
+
+namespace mod_wiki\backup;
+
+/**
+ * Unit tests for wiki restoration process
+ *
+ * @package   mod_wiki
+ * @copyright 2024 Laurent David <laurent.david@moodle.com>
+ *
+ * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
+ */
+class restore_format_test extends \advanced_testcase {
+
+    /**
+     * Data provider for test_duplicating_wiki_removes_unwanted_formats.
+     *
+     * @return array[]
+     */
+    public static function restore_format_test_provider(): array {
+        return [
+            'creole' => [
+                'data' => 'creole',
+                'expected' => 'creole',
+            ],
+            'html' => [
+                'data' => 'html',
+                'expected' => 'html',
+            ],
+            'wikimarkup' => [
+                'data' => 'nwiki',
+                'expected' => 'nwiki',
+            ],
+            'wrong format' => [
+                'data' => '../wrongformat123',
+                'expected' => 'wrongformat',
+            ],
+        ];
+    }
+
+    /**
+     * Test that duplicating a wiki removes unwanted / invalid format.
+     *
+     * @param string $format The format of the wiki.
+     * @param string $expected The expected format of the wiki after duplication.
+     *
+     * @covers       \restore_wiki_activity_structure_step
+     * @dataProvider restore_format_test_provider
+     */
+    public function test_duplicating_wiki_removes_unwanted_formats(string $format, string $expected): void {
+        global $DB;
+
+        $this->resetAfterTest();
+        $this->setAdminUser();
+
+        // Make a test course.
+        $generator = $this->getDataGenerator();
+        $course = $generator->create_course();
+        $wiki = $generator->create_module('wiki', array_merge(['course' => $course->id, 'defaultformat' => $format]));
+        // Duplicate the wiki.
+        $newwikicm = duplicate_module($course, get_fast_modinfo($course)->get_cm($wiki->cmid));
+        // Verify the settings of the duplicated activity.
+        $newwiki = $DB->get_record('wiki', ['id' => $newwikicm->instance]);
+        $this->assertEquals($expected, $newwiki->defaultformat);
+    }
+}
diff --git a/mod/wiki/tests/wikiparser_test.php b/mod/wiki/tests/wikiparser_test.php
index 3ce41fd87a9..d267cb5b517 100644
--- a/mod/wiki/tests/wikiparser_test.php
+++ b/mod/wiki/tests/wikiparser_test.php
@@ -39,7 +39,7 @@ require_once($CFG->dirroot . '/mod/wiki/parser/parser.php');
  *
  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  */
-class wikiparser_test extends \basic_testcase {
+class wikiparser_test extends \advanced_testcase {
 
     /**
      * URL inside the clickable text of some link should not be turned into a new link via the url_tag_rule.
@@ -332,4 +332,52 @@ class wikiparser_test extends \basic_testcase {
         $this->assertNotEquals(false, $section);
     }
 
+    /**
+     * Test that format that are not supported are raising an exception
+     *
+     * @param string $format
+     * @param string $expected
+     * @covers \wiki_parser_proxy::parse
+     * @dataProvider format_parser_provider
+     */
+    public function test_format_parser(string $format, string $expected) {
+        $this->resetAfterTest();
+        $this->setAdminUser();
+        $generator = $this->getDataGenerator();
+        $course = $generator->create_course();
+        $wiki = $generator->create_module('wiki', array_merge(['course' => $course->id, 'defaultformat' => $format]));
+        $wikigenerator = $this->getDataGenerator()->get_plugin_generator('mod_wiki');
+        if ($expected === 'exception') {
+            $this->expectException(\moodle_exception::class);
+        }
+        $page = $wikigenerator->create_page($wiki);
+        $version = wiki_get_current_version($page->id);
+        $this->assertEquals($expected, $version->contentformat);
+    }
+
+    /**
+     * Data provider for test_format_parser
+     *
+     * @return array[]
+     */
+    public static function format_parser_provider(): array {
+        return [
+            'creole' => [
+                'data' => 'creole',
+                'expected' => 'creole',
+            ],
+            'html' => [
+                'data' => 'html',
+                'expected' => 'html',
+            ],
+            'wikimarkup' => [
+                'data' => 'nwiki',
+                'expected' => 'nwiki',
+            ],
+            'wrong format' => [
+                'data' => '../wrongformat123',
+                'expected' => 'exception',
+            ],
+        ];
+    }
 }