Anti-trip mechanism for limiting the travel of a timepiece balance including a pin projecting from a staff, including a flexible multistable or bistable element carrying an anti-trip stop member and which is fixed, via flexible and elastic connecting members, to a rigid structural element of a timepiece movement. One end of said anti-trip stop member is arranged, according to the angular position of the balance, to interfere with the trajectory of the pin, and to perform the function of a stop if the balance exceeds its normal angular travel.Each anti-trip stop member includes two arms whose respective ends each interfere with the trajectory of the pin.