  We present a calculation of the NLO QCD corrections for Higgs-boson pair
production in gluon fusion including effects of anomalous couplings within
Standard Model Effective Field Theory (SMEFT). We study effects of different
truncation options of the EFT expansion in $1/\Lambda$ and of double operator
insertions, both at total cross-section level as well as for the distribution
of the invariant mass of the Higgs-boson pair, at $\sqrt{s}=13$ TeV. The NLO
corrections are implemented in the generator $\texttt{ggHH_SMEFT}$ in the
$\texttt{Powheg-Box-V2}$ framework.
