Building on x64 Linux fail about openbor HOT 2 CLOSED

source/gamelib/packfile.c: In function 'casesearch':
source/gamelib/packfile.c:324:33: error: 'sprintf' may write a terminating nul past the end of the destination [-Werror=format-overflow=]
         sprintf(fullpath, "%s/%s", dir, entry->d_name);
                                 ^
source/gamelib/packfile.c:324:9: note: 'sprintf' output 2 or more bytes (assuming 257) into a destination of size 256
         sprintf(fullpath, "%s/%s", dir, entry->d_name);
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [Makefile:655: source/gamelib/packfile.o] Error 1