  Large liquid argon TPC detector programs such as LBNE and LAGUNA-LBNO will be
able to make measurements of the proton lifetime which will outperform
Cherenkov detectors in the proton decay channel $p \rightarrow K^{+}\nu$. At
the large depths which are proposed for such experiments, a non-negligible
source of isolated charged kaons may be produced in the showers of cosmogenic
muons. We present an estimate of the cosmogenic muon background to proton decay
in the $p \rightarrow K^{+}\nu$ channel. The simulation of muon transport to a
depth of 4 km w.e, is performed in the MUSIC framework and the propagation of
muons and secondary particles through to a cylindrical 20 kt LAr target is
performed using Geant4. An exposure time of 100 years is considered, with a
rate of $< 0.0012$ events/kt/year at 90$\%$ CL predicted from our simulations.
