  We describe a possibility to explain the $2.6\sigma$ deviation from lepton
flavour universality observed by the LHCb collaboration in $B^+\to
K^+\ell^+\ell^-$ decays in the context of minimal composite Higgs models. We
find that a sizable degree of compositeness of partially composite muons can
lead to a good agreement with the experimental data. Our construction predicts
a new physics contribution to $B_s$-$\bar{B}_s$ mixing. Additionally, it
accounts for the deficit in the invisible $Z$ width measured at LEP.
