diff --git a/authsaml/auth.php b/authsaml/auth.php
index 8e7405d..05af3ff 100644
--- a/authsaml/auth.php
+++ b/authsaml/auth.php
@@ -37,6 +37,7 @@ public function __construct()
 
         // $this->cando['external'] = true;
 
+        $this->cando['modGroups'] = true;
         $this->cando['external'] = true;
         $this->cando['logoff'] = true;
         $this->success = true;
diff --git a/authsaml/saml.php b/authsaml/saml.php
index 7834faa..12082d9 100644
--- a/authsaml/saml.php
+++ b/authsaml/saml.php
@@ -369,8 +369,8 @@ public function modifyUser($username, $changes) {
             $userinfo[$field] = $value;
         }
 
-        $groups   = join(',', $userinfo['grps']);
-        $groups   = array_map('urlencode', $groups);
+        $groups   = array_map('urlencode', $userinfo['grps']);
+        $groups   = join(',', $groups);
 
         $userline = join(':', array($newuser, $userinfo['name'], $userinfo['mail'], $groups))."\n";