  It is well known that massive 3D gravity admits solutions that describe
Lifshitz black holes as those considered in non-relativistic holography.
However, the determination of the mass of such black holes remained unclear as
many different results were reported in the literature presenting
discrepancies. Here, by using a robust method that permits to tackle the
problem in the strong field regime, we determine the correct mass of the
Lifshitz black hole of the higher-derivative massive gravity and compare it
with other results obtained by different methods. Positivity of the mass
spectrum demands an odd normalization of the gravity action. In spite of this
fact, the result turns out to be consistent with computations inspired in
holography.
