% First this:
\usepackage{multicol}

% Then the patch:
\usepackage{etoolbox}

\makeatletter
\patchcmd{\multi@column@out}
   { \global \@mparbottom \z@}
   { \global \@mparbottom \z@ \global\@textfloatsheight\z@}
   {\typeout{patched}}
   {\ERROR}
\makeatother

% Then start the document:

\begin{document}

...

\end{document}