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 sys- tems. 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 concepts common to all such frameworks: state modeling, commands, interpreting commands, preconditions, and agreement checking.