```ruby
class FontPtSerif < Cask
  url 'http://www.fontstock.com/public/PTSerif.zip'
  homepage 'http://www.paratype.com/public/'
  version '1.001'
  sha1 'b445d4cc49a18581852bab27a204d4b4a44a403f'
  font 'PTF55F.ttf'
  font 'PTF56F.ttf'
  font 'PTF75F.ttf'
  font 'PTF76F.ttf'
  font 'PTZ55F.ttf'
  font 'PTZ56F.ttf'
end
```

Update PT serif to sha256 checksums
user
```ruby
class FontPtSerif < Cask
  url 'http://www.fontstock.com/public/PTSerif.zip'
  homepage 'http://www.paratype.com/public/'
  version '1.001'
  sha256 '74eec886edb58899018448e69cfab7032dd2ce8ff69a44c18f88a7d2a7bf3b26'
  font 'PTF55F.ttf'
  font 'PTF56F.ttf'
  font 'PTF75F.ttf'
  font 'PTF76F.ttf'
  font 'PTZ55F.ttf'
  font 'PTZ56F.ttf'
end
```
assistant