# List of custom float type in Memoir is misformatted

I am writing a document with memoir, and am having a formatting problem with my List of Listings.

I am setting up the Listing type as follows:

\newfloat[chapter]{listing}{lol}{Listing}
\newcommand{\listlistingname}{List of Listings}
\newlistof{listoflistings}{lol}{\listlistingname}


My \listoflistings invocation, however, is producing the following result:

The built-in lists (\listoffigures, \listoftables) are working properly. I have also examined the contents of the .lol file, and it is indistinguishable form the lot and lof files. I do not have listing, lstlistings, or listings loaded.

How might I debug this problem and get my list of listings to behave correctly?

\documentclass{memoir}

\newfloat[chapter]{listing}{lol}{Listing}
\newcommand{\listlistingname}{List of Listings}
\newlistof{listoflistings}{lol}{\listlistingname}
% "The other part of creating a new 'List of...', is to specify the formatting of
% the entries" (memoir manual, section 9.3)

\begin{document}

\listoflistings

\chapter{One}

\begin{listing}
Here goes some content.
\caption{\label{lst:one} Listing 1}
\end{listing}

\begin{listing}
Here goes some content.
\caption{\label{lst:two} Listing 2}
\end{listing}

\chapter{Two}

\begin{listing}
Here goes some content.
\caption{\label{lst:three} Listing 3}
\end{listing}

\end{document}