We consider the Hele-Shaw problem (without surface tension) and make the observation that the free boundary –represented by the hodograph transform of the solution- essentially solves a parabolic integro-differential equation. This equation linearizes (under a flatness assumption) to a nonlocal parabolic equation with rough coefficients, for which regularity estimates are available. This method yields that under flatness assumption, the free boundary is given locally by the graph of a function whose spatial gradient is Holder continuous in space and time. Joint work with Hector Chang-Lara.