Incorrect target of \label link produced by hyperref

In the following code, the command \label{my} appears on page 4, as well \pageref{my} says "4", but the hyperlink points to the page one. Why is that?

\documentclass{book}
\usepackage{hyperref}
\usepackage{lipsum}

\begin{document}

% Four pages of text.
\lipsum[1-20]

% The label is on fourth page.
\label{my}

% Buggy pageref. It produces the number 4, but the link leads to the first page.
\pageref{my}

\end{document}

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Most definitely not a bug. The \label command attaches a marker to the nearest structure -- \section, \caption, etc -- that can receive an anchor. Your document has no anchorable structures at all; hence the default anchor, the start of the document, applies. Use the \pantomsection command to create additional anchors for \label commands. –  Mico Mar 23 '12 at 3:05

It's not a bug; there's no anchor; \label by itself does not place an hyperlink-anchor, so obviously your hyperlink won't take you to the place where you placed \label; you can use \phantomsection to create an anchor at a given location:

\documentclass{book}
\usepackage{hyperref}
\usepackage{lipsum}

\begin{document}

\lipsum[1-20]

\phantomsection\label{my}\newpage

\pageref{my}

\end{document}

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