No newline in box/text mixed layout

Question

I want to mix boxes and characters in a paragraph. But it looks sometimes no newline inserted, a box is overfull and the following character goes outside the paper.

Here is MWE (graphics are included to mimic boxes of different sizes)

\documentclass[a4paper,12pt]{article}

\usepackage[%
includeheadfoot, headheight=15pt, headsep=14pt, footskip=25pt,
top=8mm, bottom=8mm, left=1cm, right=1cm]{geometry}

\usepackage{pgffor}
\usepackage{varwidth}
\usepackage[demo]{graphicx}

\newcommand{\layoutimgs}[1] {%
    \noindent%
    \foreach \imgh / \imgw in {#1} {%
    \includegraphics[height=\imgh,width=\imgw]{demo}%
    ;\hfill%
    }%
}

\begin{document}
\layoutimgs{{11mm}/{157mm}, {5mm}/{191mm}}
\end{document}

The output is:

The 2nd box gets overfull and the 2nd semicolon is missing.

I expect a new line starts after the 1st semicolon.