diff --git a/after/syntax/c.vim b/after/syntax/c.vim
index 2b209be..539531f 100644
--- a/after/syntax/c.vim
+++ b/after/syntax/c.vim
@@ -27,7 +27,7 @@ let g:c_doxygen = get(g:, 'c_doxygen', 1)
 if exists('g:c_doxygen') && g:c_doxygen
   syn region cDoxygen oneline matchgroup=cComment start='\/\/\/\s*[\\@]brief\s\+' end='$'
   syn region cDoxygen oneline matchgroup=cComment start='\/\/\/\s*[\\@]tparam\s\+' end='\(\s.*$\|$\)'
-  syn region cDoxygen oneline matchgroup=cComment start='\/\/\/\s*[\\@]param\(\[\(\|in\|out\|inout\)\]\)\=\s\+' end='\(\s.*$\|$\)'
+  syn region cDoxygen oneline matchgroup=cComment start='\/\/\/\s*[\\@]param\(\[\(\|in\|out\|in,out\)\]\)\=\s\+' end='\(\s.*$\|$\)'
   syn match cDoxygenTodo 'todo' contained
   syn region cComment oneline start='\/\/\/\s*[\\@]\zetodo\s\+' end='$' contains=cDoxygenTodo
   hi default link cDoxygen SpecialComment