diff --git a/common/redisclient.go b/common/redisclient.go
index b5a6070..1e4126d 100644
--- a/common/redisclient.go
+++ b/common/redisclient.go
@@ -136,14 +136,15 @@ func (client *RedisClient) QueryCuboid(cuboid Cuboid, fn func(*Block)) (count in
 		key   int64
 	)
 
-	for ; ; count++ {
-		if size, err = client.readBulkString(&data); err != nil {
+	for s := client.scratch[:]; ; count++ {
+		p := &s
+		if size, err = client.readBulkString(p); err != nil {
 			return
 		}
 		if size <= 0 {
 			break
 		}
-		if key, err = DecodeStringFromBytes(data[:size]); err != nil {
+		if key, err = DecodeStringFromBytes((*p)[:size]); err != nil {
 			return
 		}
 		block.Coord = PlainToCoord(key)