Total intensity images (black contours) of BL Lac obtained with 86 GHz GMVA observations. Contours are drawn at 0.77, 1.53, 3.02, 5.96, 11.74, 23.15, 45.65, and 90% of the peak (1.528 Jy beam⁻¹) registered in May 2011. The restoring beams, shown at the bottom-left corner, range from 0.04 × 0.1 mas to 0.08 × 0.22 mas in FWHM. Model-fit components (blue circles) are overlaid on the maps. In May 2016 and March 2017, an additional component appears upstream of the core.