diff --git a/phpgwapi/inc/class.egw_session_memcache.inc.php b/phpgwapi/inc/class.egw_session_memcache.inc.php
index 2cd4151083..5e4fb1913e 100644
--- a/phpgwapi/inc/class.egw_session_memcache.inc.php
+++ b/phpgwapi/inc/class.egw_session_memcache.inc.php
@@ -240,6 +240,8 @@ class egw_session_memcache
 		if (self::DEBUG > 1) error_log("\n memcache in cutbyte mb $id:$n:".print_r(mb_substr($data,$offset,$len,'ascii'),true));
 		if (self::DEBUG > 1) error_log("\n memcache in cutbyte norm $id:$n:".print_r(substr($data,$offset,$len),true));
 
+		if (is_null($len)) $len = self::_bytes($data) - $offset;
+
 		return self::$mbstring_func_overload ? mb_substr($data,$offset,$len,'ascii') : substr($data,$offset,$len);
 	}
 
diff --git a/phpgwapi/inc/class.global_stream_wrapper.inc.php b/phpgwapi/inc/class.global_stream_wrapper.inc.php
index ecb30a2f83..81a0bf7524 100644
--- a/phpgwapi/inc/class.global_stream_wrapper.inc.php
+++ b/phpgwapi/inc/class.global_stream_wrapper.inc.php
@@ -125,6 +125,8 @@ class global_stream_wrapper
 	 */
 	private static function _cut_bytes(&$data,$offset,$len=null)
 	{
+		if (is_null($len)) $len = self::_bytes($data) - $offset;
+
 		return self::$mbstring_func_overload ? mb_substr($data,$offset,$len,'ascii') : substr($data,$offset,$len);
 	}