  We show that a simple modification to an optical table with pneumatic
vibration isolation can be used to actively reduce the long term drift in the
tilt of the table by nearly a factor of 1000. Without active stabilization, we
measure a root-mean-square (RMS) tilt variation of \SI{270}{\upmu rad} over
three days. The active stabilization can be used to limit the tilt to
\SI{0.35}{\upmu rad} RMS over the same time period. This technique can be used
to minimize drift in tilt-sensitive experiments.
