Partition type misinterpreted by Parted

I am learning Linux and now, as an exercise, I am using parted on my pendrive. I enter Parted, selecting my pendrive. There is no partitions and I create one with mkpart name ext4 1 3200. When I print all of the partitions, there is one correctly labeled as ext4. Now when I leave parted and enter it again, the just created partition is now labeled as ntfs. Why is it happening?