sprintf "%d" now gives the same error as sprintf "%s": $ perl6 -e 'sprintf "%s"' Too many directives: found 1, but no arguments after the format string
$ perl6 -e 'sprintf "%d"' Too many directives: found 1, but no arguments after the format string This was fixed with commit https://github.com/perl6/nqp/commit/f2577cb116. I added a test to S32-str/sprintf.t with commit https://github.com/perl6/roast/commit/8fc7d0289c I'm closing this ticket now.