This patch deletes the line free(fontnames[fix]); from /sys/src/cmd/acme/acme.c:/^rfget. The strings fontnames[i] do not necessarily come from malloc: Initially, they are statically allocated. Other code that sets fontnames[i] does not free first; for example /sys/src/cmd/acme/acme.c:/^threadmain /sys/src/cmd/acme/rows.c:/^rowloadfonts The following seems to crash acme reliably (and does not with this patch): Run it like /386/bin/acme to avoid any Load or command-line changes to fontnames. Put the text Font var /lib/font/bit/lucidasans/unicode.6.font in a window (not a tag). Execute the text with the middle button.