# Using listing for displaying Matlab code

I'm trying to display matlab code in a LaTeX document and the comments are typeset with an ugly space between letters:

\documentclass{article}

\usepackage{listings}
\lstset{language=Matlab}
\lstset{tabsize=2}

\begin{document}
\begin{lstlisting}
function gramschmidt(A) %The columns of A are the initial basis to the subspace
\end{lstlisting}
\end{document}


results in

Is there a way to improve the kerning (or whatever its called) of the text in the comments?

-
\lstset{flexiblecolumns=true}