  We report a complete analytical expression for the one-loop correction to the
ac conductivity $\sigma(\omega)$ of a disordered two-dimensional electron
system in the diffusive regime. The obtained expression includes the weak
localization and Altshuler-Aronov corrections as well as the corrections due to
superconducting fluctuations above superconducting transition temperature. The
derived expression has no $1/(i\omega)$ divergency in the static limit,
$\omega\to 0$, in agreement with general expectations for the normal state
conductivity of a disordered electron system.
