PS1 images of location of SN 2018cnf in Pan-STARRS r and w filters. Top left panel: stacked image (limiting magnitude r >  22.1 mag) obtained by combining several r-band images obtained in 2009−2010 when no sources were visible at the position of SN 2018cnf. Other panels show single-epoch images obtained in October 2012 (top centre), November 2015 (top right), December 2015 (at the time of the brightest outburst; bottom left), August 2017 (bottom centre), and August 2018 (when the SN had already exploded; bottom right). We note the remarkable variability of the progenitor star started at least about six years before the explosion of SN 2018cnf.