TikZ & Babel incompatibility

Question

The following M(not)WE works without the importation of babel. How can I fix this ?

\documentclass{article}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{tkz-tab}
\usetikzlibrary{calc}
\usepackage[french]{babel,varioref}
\newcommand\commentthis[3]{
    \coordinate (M) at ($(#1)!.5!(#2)$); 
    \path
        (M.east) +(.75,0) node[right,blue]{#3}
    ;
}
\begin{document}
\begin{tikzpicture}
    \tkzTabInit[
        espcl = 1.5,
    ]{
        $x$                         /1,
        Signe de\ $-x+3$           /1.5
    }{%
         $-1$, $+1$
    }
\tkzTabLine { z , + , z }
\commentthis{T21}{T22}{TEST}

\end{tikzpicture}
\end{document}

In the log there is :

LaTeX Font Info:    External font `cmex10' loaded for size
(Font)              <7> on input line 69.
LaTeX Font Info:    External font `cmex10' loaded for size
(Font)              <5> on input line 69.
./tab-sign-deco.tex:77: Package tikz Error: + or - expected.
See the tikz package documentation for explanation.
Type  H <return>  for immediate help.
 ...
l.77     \signline{T21}{T22}{$3$}
? 
./tab-sign-deco.tex:77: Emergency stop.
 ...
l.77     \signline{T21}{T22}{$3$}
End of file on the terminal!