Fonts & Character Sets ⇒ One font for text and another one for maths

[Tobias_Denmark]

I'm trying to implement Siarhei Khirevich (http://www.khirevich.com/latex/font/) suggestion on charter font for text and default text font for math envirements. It is working, but I get a warning like tihs:

“package mathdesign warning no font specified on input line 175”

How can I get this warning to disappear or disable it or rewrite my code so the warning it's not being activated?

Code: Select all

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{charter}
\usepackage[expert]{mathdesign}
\begin{document}
This is a test:
\begin{equation}
	P_p(z) = P_p(z_0) + \int_{z_0}^z{\frac{\partial P_f}{\partial z}\,\mathrm{d}z}
\end{equation}
\end{document}