  We confront the perturbativity problem in the real scalar quintuplet minimal
dark matter model. In the original model, the quintuplet quartic self-coupling
inevitably hits a Landau pole at a scale $\sim 10^{14}$ GeV, far below the
Planck scale. In order to push up this Landau pole scale, we extend the model
with a fermionic quintuplet and three fermionic singlets which couple to the
scalar quintuplet via Yukawa interactions. Involving such Yukawa interactions
at a scale $\sim 10^{10}$ GeV can not only keep all couplings perturbative up
to the Planck scale, but can also explain the smallness of neutrino masses via
the type-I seesaw mechanism. Furthermore, we identify the parameter regions
favored by the condition that perturbativity and vacuum stability are both
maintained up to the Planck scale.
