diff --git a/phpgwapi/inc/class.auth.inc.php b/phpgwapi/inc/class.auth.inc.php
index 9ccffe3369..696987845a 100644
--- a/phpgwapi/inc/class.auth.inc.php
+++ b/phpgwapi/inc/class.auth.inc.php
@@ -76,11 +76,11 @@ class auth
 		// retrieve the timestamp regarding the last change of the password from auth system and store it with the session
 		static $alpwchange_val;
 		static $pwdTsChecked;
-		if (is_null($pwdTsChecked) && is_null($alpwchange_val))
+		if (is_null($pwdTsChecked) && is_null($alpwchange_val) || (string)$alpwchange_val === '0')
 		{
 			$alpwchange_val =& egw_cache::getSession('phpgwapi','auth_alpwchange_val'); // set that one with the session stored value
 			// initalize statics - better readability of conditions
-			if (is_null($alpwchange_val))
+			if (is_null($alpwchange_val) || (string)$alpwchange_val === '0')
 			{
 				$backend_class = 'auth_'.$GLOBALS['egw_info']['server']['auth_type'];
 				$backend = new $backend_class;
diff --git a/phpgwapi/inc/class.auth_ads.inc.php b/phpgwapi/inc/class.auth_ads.inc.php
index 0fda5f835a..41942dfda8 100644
--- a/phpgwapi/inc/class.auth_ads.inc.php
+++ b/phpgwapi/inc/class.auth_ads.inc.php
@@ -207,7 +207,7 @@ class auth_ads implements auth_backend
 			$username = $GLOBALS['egw']->accounts->id2name($account_id);
 		}
 		// Check the old_passwd to make sure this is legal
-		if(!$admin && !$adldap->authenticate($username, $old_passwd))
+		if(!$admin && !$this->authenticate($username, $old_passwd))
 		{
 			//error_log(__METHOD__."() old password '$old_passwd' for '$username' is wrong!");
 			return false;