Missing argument 2 for truncate_utf8()

When viewing "All 404s" (admin/reports/404/all) I get the following warning repeated for each row in the table:

warning: Missing argument 2 for truncate_utf8(), called in pagenotfound_reports.module on line 151

Line 151, part of the table row declaration:

  truncate_utf8(truncate_utf8($dblog->message, 56, TRUE, TRUE)),

I'd submit a patch but I don't know what will be the best solution, whether to remove the nested truncate_utf8() call or to add the missing arguments to the outer truncate_utf8(). Not sure what is by design here.

Thanks!