Every CFML engine I can find - Adobe ColdFusion 10, 11 and 2016, Lucee 4.5 and 5 - has a bug where if you try to use randRange() on 231-1 (MAX_INT) it will overflow and give you a negative number. See for yourself: http://trycf.com/gist/726e96e5c5e9498b32a2/acf2016. Here is a better way that supports not only MAX_INT but also MAX_LONG (263-1).