In this note, we consider the problem of output regulation for linear single-input-single-output systems in presence of time-varying measurement constraint. It is shown bow an internal model-based regulator, processing a saturated uncertain function of the regulated error, can be designed in order to secure asymptotic tracking/rejection of exosystem-generated references/disturbances. The design is semiglobal\ in the initial state of the plant and of the exosystem and requires the zero dynamics of the controlled system to be weakly minimum-phase.