diff --git a/htdocs/caldav.php b/htdocs/caldav.php
index 5c4bdb45..a1763b82 100644
--- a/htdocs/caldav.php
+++ b/htdocs/caldav.php
@@ -102,7 +102,7 @@ if ( ! ($request->IsPrincipal() || isset($request->collection) || $request->meth
     @ob_flush(); exit(0);
   }
 }
-param_to_global('add_member', '.*', 'add-member');
+param_to_global('add_member', null, 'add-member');
 $add_member = isset($add_member);
 
 try {