  We show that in ideal hydrodynamic simulations of heavy-ion collisions,
initial state fluctuations result in an increase of the mean transverse
momentum of outgoing hadrons, $\langle p_t\rangle$. Specifically, $\langle
p_t\rangle$ is larger by a few percent if realistic fluctuations are
implemented than with smooth initial conditions, the multiplicity and impact
parameter being kept fixed. We show that result can be traced back to the fact
that for a given total entropy, the initial energy contained in the fluid is
larger if the density profile is bumpy. We discuss the implication of these
results for the extraction of the equation of state of QCD from experimental
data.
