Save/Restore Ruby's Random

I'm trying to create a game, which I want to always run the same given the same seed. That means that random events - be them what they may - will always be the same for two players using the same seed. However, given the user's ability to save and load the game, Ruby's Random would reset every time the save loaded, making the whole principle void if two players save and load at different points.

The only solution I have imagined for this is, whenever a save file is loaded, to generate the same number of points as before, and thus getting Ruby's Random to the same state as it was before load. However, to do that I'd need to extend it so a counter is updated every time a random number is generated.

Does anyone know how to do that or has a better way to restore the state of Ruby's Random?

PS: I cannot use an instance of Random (Random.new) and Marshall it. I have to use Ruby's default.