diff --git a/htdocs/admin/dav.php b/htdocs/admin/dav.php
index 90b82421702..53971743b20 100644
--- a/htdocs/admin/dav.php
+++ b/htdocs/admin/dav.php
@@ -168,6 +168,9 @@ print "<br>";
 // Define $urlwithroot
 $urlwithouturlroot=preg_replace('/'.preg_quote(DOL_URL_ROOT, '/').'$/i', '', trim($dolibarr_main_url_root));
 $urlwithroot=$urlwithouturlroot.DOL_URL_ROOT;		// This is to use external domain name found into config file
+if ($_SERVER['HTTPS'] == 'on' || $_SERVER['REQUEST_SCHEME'] == 'https') {
+	$urlwithroot = str_replace('http://', 'https://', $urlwithroot);
+}
 //$urlwithroot=DOL_MAIN_URL_ROOT;					// This is to use same domain name than current