Incorrect Hyperref links with memoir and breqn

Question

Consider the following MWE

\documentclass[11pt,oneside]{memoir}

\usepackage{breqn}
\usepackage{hyperref}

\begin{document}
\mainmatter

\begin{dmath}\label{eq:1}
 1 + 1 = 2,
\end{dmath}
\newpage
\begin{dmath}\label{eq:2}
 1 + 1 = 2,
\end{dmath}

\newpage
\ref{eq:2}

\end{document}

where after running the document through pdflatex a couple of times we find that clicking on the reference to equation 2 actually takes us to equation 1. If the dmath blocks are replaced with regular equations everything works as expected.

Answer 1

This might be an incompatibility between hyperref and breqn. You can get around this by using the equation environment or by setting a verbatim \phantomsection before your dmath environment:

\documentclass{book}

\usepackage{breqn}
\usepackage{hyperref}

\begin{document}

\phantomsection
\begin{dmath}[label={eq:1}]
 1 + 1 = 2,
\end{dmath}

\newpage
\phantomsection
\begin{dmath}[label={eq:2}]
 1 + 1 = 2,
\end{dmath}

\newpage
See equation~\ref{eq:2}.

\end{document}