We report an error in the article 'Optical polarization map of the Polaris Flare with RoboPol', published in 2015, MNRAS, 452, 715 (hereafter Panopoulou et al. 2015). The error only affects the conversion of the Electric Vector Position Angle (EVPA) from the celestial system (in which the values are correct) to the Galactic system. The formula used to convert the polarization angles from the celestial to the Galactic system, taken from Stephens et al. (2011) was found to be incomplete. In the following, we explain the formula used by these authors and its limitations, and describe the correction.