plen = (addr->prefix == NULL)? 0 : Ustrlen(addr->prefix);
slen = Ustrlen(addr->suffix);
-return string_sprintf("%.*s@%s", (at - addr->address - plen - slen),
+return string_sprintf("%.*s@%s", (int)(at - addr->address - plen - slen),
addr->address + plen, at + 1);
}