diff --git a/auth.php b/auth.php
index 6aa528247aba3c73d1c38aff571c7a0300eef34b..e188785b6dfeafec502358525e5e4c634989cc1f 100644
--- a/auth.php
+++ b/auth.php
@@ -41,7 +41,7 @@ class auth_plugin_authuffd extends DokuWiki_Auth_Plugin
 			'code' => $INPUT->get->str('code'),
 			'redirect_uri' => $this->getOAuth2RedirectURI()
 		);
-		$ok = $http->get($this->getConf('baseurl') . '/oauth2/token?' . http_build_query($params, '', '&', PHP_QUERY_RFC3986));
+		$ok = $http->post($this->getConf('baseurl') . '/oauth2/token', $params);
 		if (!$ok || $http->status != 200)
 			return false;
 		return json_decode($http->resp_body)->access_token;