Odd minus style when drawing american voltage

Question

Looking closely at the image produced by circuitikz, I find that the minus sign of an american voltage looks rather odd. The alignment seems off and the sign seems much too wide. Is there a way to align the minus sign to the horizontal line of the plus sign and make it just as wide?

This is the code snippet that reproduces the result:

\documentclass{book}
\usepackage{circuitikz}
\begin{document}
\begin{figure}[h]
    \begin{circuitikz}[american voltages]
        \draw
        (4,-1) to[short] (4,-2)
        (5,-1) to[short] (5,-2);
        \draw (4,-2) to[open,v_>=$U_S$] (5,-2);
    \end{circuitikz}
\end{figure}
\end{document}

Answer 1

This is a bug; thanks for noticing. The new version will have this fixed and, as a bonus, a way to customize the appearance of the symbols.

See https://github.com/circuitikz/circuitikz/pull/196