insecure(?) format string

insecure-fmt.txt

[~/src/SillyMUD/src]$ make
gcc -g -DIMPL_SECURITY -DNEW_RENT -DLEVEL_LOSS -DNEWEXP -DGROUP_NAMES -Werror -DIMPL_SECURITY -DNEW_RENT -DLEVEL_LOSS -DNEWEXP -DGROUP_NAMES  -c -o act.wizard.o act.wizard.c
act.wizard.c:243:24: error: format string is not a string literal
      (potentially insecure) [-Werror,-Wformat-security]
       sprintf(string, tmp);
                       ^~~
/usr/include/secure/_stdio.h:47:56: note: expanded from macro 'sprintf'
  __builtin___sprintf_chk (str, 0, __darwin_obsz(str), __VA_ARGS__)
                                                       ^
...
7 errors generated.
make: *** [act.wizard.o] Error 1