  We present a phenomenological analysis of the magnetoelastic properties of
CeCo$_{0.85}$Fe$_{0.15}$Si at temperatures close to the N\'eel transition
temperature $T_N$. Using a Landau functional we provide a qualitative
description of the thermal expansion, magnetostriction, magnetization and
specific heat data. We show that the available experimental results [Journal of
Physics: Condensed Matter 28 346003 (2016)] are consistent with the presence of
a structural transition at $T_s\gtrsim T_N$ and a strong magnetoelastic
coupling. The magnetoelastic coupling presents a Janus-faced effect: while the
structural transition is shifted to higher temperatures as the magnetic field
is increased, the resulting striction at low temperatures decreases. The strong
magnetoelastic coupling and the proximity of the structural transition to the
onset temperature for magnetic fluctuations, suggest that the transition could
be an analogue of the tetragonal to orthorhombic observed in Fe-based
pcnictides.
