[SOLVED] Pandoc: \textbackslash appears before \begin{document}

Pandoc: \textbackslash appears before \begin{document}

I'm using pandoc in markdown+raw_tex mode to generate PDFs through either Xetex or Luatex. When I generate the intermediate TeX representation, the generation fails because the processor encounters an \textbackslash before it meets \begin{document}. Specifically, the tex file it tries to process contains:

\makeatletter

\textbackslash renewcommand\{@mkboth\}{2} \makeatother
... stuff here ...
\title{My Title}
\usepackage{etoolbox}
\makeatletter
\providecommand{\subtitle}[1]{% add subtitle to \maketitle
  \apptocmd{\@title}{\par {\large #1 \par}}{}{}
}
\makeatother
\subtitle{foo}
\author{Me}
\date{}

\begin{document}
... more stuff here ...

In other words, instead of calling \renewcommand it somehow encoded the \ into a \textbackslash.

My markdown preamble does in fact contain

header-includes: |
    ...
    \makeatletter
    \renewcommand{\@mkboth}[2]{}
    \makeatother

So I'm wondering why it felt the need to tex-encode something from the preamble and how I can avoid it.

Solution

As explained here, the latex code in the preamble must be marked up as such:

header-includes: |
  ```{=latex}
  \makeatletter
  \renewcommand{\@mkboth}[2]{}
  \makeatother
  ```