# Cleveref not working with Greek/Xetex

I've been having some issues with cleveref; Whenever I include it it throws the following error:

\$ xelatex mwe.tex
...
! Undefined control sequence.
\@begindocumenthook ...sname extras\cref@language
\endcsname }\@ifundefined...
l.16 \begin{document}


MWE:

\documentclass[a4paper,12pt,final]{memoir}
\usepackage[no-math]{fontspec}
\usepackage{csquotes}
\usepackage{polyglossia}
\setmainlanguage[variant=mono]{greek}
\setotherlanguage{english}

%\setmainfont[Mapping=tex-text,Ligatures=TeX,Numbers=OldStyle]{Linux Libertine O}
\usepackage[p,osf]{libertine}

\usepackage{hyperref}
\usepackage{cleveref}

\begin{document}
paok ekdromes ναρκωτικά
\end{document}

• cleveref has no predefined settings for greek. You will have to define them. – Ulrike Fischer Apr 19 '18 at 20:31
• Could you be more specific? Are you talking about the ref names? Because I can't see how they apply in this MWE, as there are no refs. – svart Apr 19 '18 at 20:39
• It is trying to do set-up code at the beginning of the document. It apparently needs the stuff defined here, even though nothing has been used yet. As you can see, the error is at \begin{document}, so the content of the document itself is irrelevant - it hasn't been read yet. – cfr Apr 19 '18 at 23:37