  The bending of lightrays by the gravitational field of a ``lens'' that is
moving relative to the observer is calculated within the approximation of weak
fields, small angles and thin lenses. Up to first order in $v/c$ -- and
assuming the acceleration to be much smaller than $v/c$ -- the bending angle,
time delay and redshift of the images are found to be affected by the component
of the speed of the deflector along the line of sight. The correction takes the
form of an overall factor of $1+v/c$ accompanying the mass of the deflector,
leading to an indeterminacy of the order of $v/c$ in the mass of the lens
inferred on the basis of the separation of multiple images. The consequent
correction to the microlensing lightcurve is pointed out, as well as scenarios
where the correction is potentially relevant.
