  We point out that hints of deviations from unitarity in the first row of the
CKM matrix may be explained by the presence of a single vector-like top. We
study how the stringent experimental constraints arising from CP Violation in
the kaon sector and from meson mixing such as $D^0$-$\overline{D}^0$,
$K^0$-$\overline{K}^0$ and $B^0_{d,s}$-$\overline{B}^0_{d,s}$ can be satisfied
in the proposed framework. In order for the deviations from unitarity to be of
the required size while keeping the theory perturbative, the new top quark
should have a mass $m_T \lesssim 7$ TeV which could be probed in upcoming
experiments at the energy frontier.
