Require 'bcrypt' failing on multiple operating systems, what am I missing?

I'm trying to work in a simple authentication to replace the HTTP-Auth I've got in a small Sinatra application. bcrypt-ruby gem installs fine but require 'bcrypt' always throws an error: no such file to load -- bcrypt. I've confirmed the installation in my gem list, never had a similar error with another gem and while there's a fair amount of search results for bcrypt & not found errors, none of them o开发者_Go百科ffer a solution.

Does adding this before you require 'bcrypt' help?

require 'rubygems'