Abstract: A peristaltic pump comprising a motor body (4), a cassette (1) with a casing (31) wherein are provided rotary rollers driven by a driving shaft (10) of the motor body (4) and which compress a deformable tube (25). The cassette further includes an error-preventing assembly having a platen (2) capable of taking either an active position where the driving shaft (10) actuates the rotary rollers (15) or a rest position where the rollers are fixed, and at east one finger (23) arranged on the lower part (14) of the cassette (1), the finger being capable of passing the platen (2) from the rest position to the active position.