An inflatable penile prosthesis can comprise a reservoir, an inflatable member, and a pump assembly. The pump assembly can include at least one valve comprising an entry tube interface configured to attach to the entry tube and defining an entry passageway, an entry portion adjacent to the entry tube interface, a middle portion adjacent to the entry portion, an exit portion adjacent to the middle portion, the exit portion being narrower than the middle portion, the exit portion defining an exit portion passageway and comprising multiple guides extending toward a longitudinal exit axis, the multiple guides being symmetrical about the longitudinal exit axis, the exit tube interface adjacent to the exit portion, and a poppet disposed inside the chamber, the poppet being biased to rest against the entry portion.