pdflatex vs lualatex papersize layout problem

Question

The next code produce a a6 format paper with pdflatex that fit well, but with lualatex the layout is a6 on a a4 paper sheet.

Passing a6paper option to geometry package doesn't solve the problem.

How have a correct papersize.

\documentclass[a6paper]{article}
\usepackage[margin=1.5cm]{geometry}

\begin{document}

Hello word !

\end{document}

Answer 1

Geometry has not been updated for the changes in lualatex (where they removed some \pdf... variables). Add this before \documentclass:

\RequirePackage{luatex85}