diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 18e00fcc53dc9091170b30339588df74972bf1c3..361db4e869d43d423ee2805ecdb041749e364b28 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -74,6 +74,8 @@ mkdocs:
     #- bash scripts/clean_json.sh site/mkdocs/search_index.json
     # replace broken links in 404.html
   - sed -i 's,href="" title=",href="/" title=",g' site/404.html
+  - cp site/404.html site/403.html
+  - sed -i 's/404 - Not found/403 - Forbidden/,g' site/403.html
     # compress sitemap
   - gzip < site/sitemap.xml > site/sitemap.xml.gz
   artifacts: