Pomaranch is a synchronous stream cipher submitted to eSTREAM, the ECRYPT Stream Cipher Project. The cipher is constructed as a cascade clock control sequence generator, which is based on the notion of jump registers. We present an attack which exploits the cipher’s initialisation procedure to recover the 128-bit secret key. The attack requires around 265 computations. An improved version of the attack is also presented, with complexity of the order of 252 operations.