-execute 'syn region htmlItalic start="\%(^\|\s\)\zs\*\ze[^\\\*\t ]\%(\%([^*]\|\\\*\|\n\)*[^\\\*\t ]\)\?\*\_W" end="[^\\\*\t ]\zs\*\ze\_W" keepend' . s:oneline
-execute 'syn region htmlItalic start="\%(^\|\s\)\zs_\ze[^\\_\t ]" end="[^\\_\t ]\zs_\ze\_W" keepend' . s:oneline
-execute 'syn region htmlBold start="\%(^\|\s\)\*\*\ze\S" end="\S\zs\*\*" keepend' . s:oneline
-execute 'syn region htmlBold start="\%(^\|\s\)\zs__\ze\S" end="\S\zs__" keepend' . s:oneline
-execute 'syn region htmlBoldItalic start="\%(^\|\s\)\zs\*\*\*\ze\S" end="\S\zs\*\*\*" keepend' . s:oneline
-execute 'syn region htmlBoldItalic start="\%(^\|\s\)\zs___\ze\S" end="\S\zs___" keepend' . s:oneline
+syn region mkdItalic matchgroup=mkdItalic start="\%(\*\|_\)" end="\%(\*\|_\)"
+syn region mkdBold matchgroup=mkdBold start="\%(\*\*\|__\)" end="\%(\*\*\|__\)"
+syn region mkdBoldItalic matchgroup=mkdBoldItalic start="\%(\*\*\*\|___\)" end="\%(\*\*\*\|___\)"
+execute 'syn region htmlItalic matchgroup=mkdItalic start="\%(^\|\s\)\zs\*\ze[^\\\*\t ]\%(\%([^*]\|\\\*\|\n\)*[^\\\*\t ]\)\?\*\_W" end="[^\\\*\t ]\zs\*\ze\_W" keepend' . s:oneline . s:concealends
+execute 'syn region htmlItalic matchgroup=mkdItalic start="\%(^\|\s\)\zs_\ze[^\\_\t ]" end="[^\\_\t ]\zs_\ze\_W" keepend' . s:oneline . s:concealends
+execute 'syn region htmlBold matchgroup=mkdBold start="\%(^\|\s\)\zs\*\*\ze\S" end="\S\zs\*\*" keepend' . s:oneline . s:concealends
+execute 'syn region htmlBold matchgroup=mkdBold start="\%(^\|\s\)\zs__\ze\S" end="\S\zs__" keepend' . s:oneline . s:concealends
+execute 'syn region htmlBoldItalic matchgroup=mkdBoldItalic start="\%(^\|\s\)\zs\*\*\*\ze\S" end="\S\zs\*\*\*" keepend' . s:oneline . s:concealends
+execute 'syn region htmlBoldItalic matchgroup=mkdBoldItalic start="\%(^\|\s\)\zs___\ze\S" end="\S\zs___" keepend' . s:oneline . s:concealends