(my-system
be-verbose #t
(format #f
- "pngtopnm ~a | pnmscale -reduce ~a 2>/dev/null | pnmtopng -compression 9 2>/dev/null > ~a"
+ "pngtopnm \"~a\" | pnmscale -reduce ~a 2>/dev/null | pnmtopng -compression 9 2>/dev/null > \"~a\""
old factor file))
(delete-file old)))