  Blazars constitute the most numerous source class in the known extragalactic
population of very high energy (VHE) gamma-ray sources. However, determining
their redshifts is often challenging due to weak or non-existent emission lines
in their spectra. This study focuses on two BL Lacs, KUV 00311-1938 and S2
0109+22, where previous attempts at redshift determination have faced
difficulties. By combining spectroscopic observations with photometric redshift
estimates, we tentatively assign a redshift of z = 0.634 to KUV 00311-1938 and
a likely redshift of z = 0.49 to S2 0109+22. Establishing redshift estimates
for high-redshift blazars is crucial for understanding extragalactic VHE
gamma-ray sources and their interactions with the surrounding universe.
