Since their inception, state-machine frameworks have proven their worth by finding defects in everything from the underlying AUTOSAR components of Volvo cars to digital invoicing systems. These case studies were carried out with Erlang’s commercial QuickCheck state-machine framework from Quviq, but such frameworks are now also available for Haskell, F#, Scala, Elixir, Java, etc. We present a typed state-machine framework for OCaml based on the QCheck library and illustrate a number of concepts common to all such frameworks: state modeling, commands, interpreting commands, preconditions, and agreement checking.