[NTG-context] uppercase section titles: no line breaking?

[Henning Hraban Ramm]

Hi again,
I’m trying to get uppercase titles with \WORD, but they aren’t broken into lines; while \WORD works in normal text.
What’s the matter?

Best, Hraban

%%%%%
\define[2]\MyChapter{
\WORD{#2}
}

\setuphead[chapter][
  command=\MyChapter
]

\starttext
\chapter{
\input tufte
}
\WORD{
\input knuth
}
\stoptext
%%%%%