diff -urN lua-5.1.1/src/lstrlib.c lua-5.1.1e/src/lstrlib.c --- lua-5.1.1/src/lstrlib.c Wed Apr 26 16:41:19 2006 +++ lua-5.1.1e/src/lstrlib.c Tue Oct 3 15:19:22 2006 @@ -795,7 +795,14 @@ } case 's': { size_t l; - const char *s = luaL_checklstring(L, arg, &l); + const char *s; + if (!lua_isstring(L, arg)) { + lua_getglobal(L, "tostring"); + lua_pushvalue(L, arg); + lua_call(L, 1, 1); + lua_replace(L,arg); + } + s = luaL_checklstring(L, arg, &l); if (!strchr(form, '.') && l>= 100) { /* no precision and string is too long to be formatted; keep original string */