--TEST-- MongoDB\BSON\MaxKey::jsonSerialize() with json_encode() --FILE-- new MongoDB\BSON\MaxKey]; $json = json_encode($doc); echo toJSON(fromPHP($doc)), "\n"; echo $json, "\n"; var_dump(toPHP(fromJSON($json))); ?> ===DONE=== --EXPECTF-- { "foo" : { "$maxKey" : 1 } } {"foo":{"$maxKey":1}} object(stdClass)#%d (%d) { ["foo"]=> object(MongoDB\BSON\MaxKey)#%d (%d) { } } ===DONE===