DOS Frotz sometimes won't exit when told to do so

Submitted by auraes at https://www.intfiction.org/forum/viewtopic.php?f=38&t=3937&start=10#p139443

Frotz under Dosbox: (Lubuntu 16.04.3 LTS) With some games, i can't quit the game without kill dosbox !

https://ifarchive.org/if-archive/games/zcode/Advent.z5

frotz ADVENT.Z5
>quit
Are you sure you want to quit?
>y

(I can't, I must kill Dosbox!) I recompiled the source code game Advent.inf with the latest version of the compiler and libraries and now it works.

https://ifarchive.org/if-archive/games/zcode/LostPig.z8

frotz LOSTPIG.Z8
>quit
Really all done with story?
>y

(I can't, I must kill Dosbox!) I don't have the source code of the game so I can't try to recompile it.