Pruned full node using more than 400 MB

I started running a fresh hsd node in pruned mode, using
```
$ ./bin/hsd --prune --prefix ~/.hsd_prune
```
The instructions here state that it should not require more than 400 MB: https://github.com/handshake-org/handshake-org.github.io/blob/master/src/guides/config.md#pruned-full-node-with-wallet

However, my data directory is 7.8 Gb:
```
$ du -sh hsd_prune/
7.8G hsd_prune/
```

Are the instructions out of date, or am I doing something incorrectly? Thanks!