TinyMCE Word paste and italic tag

In general the 'Paste from Word' button in TinyMCE does a good job at producing clean code. However it does wrap italics in '<i>' rather than '<em>'; I also believe it wraps bold in '<b>' rather than '<strong>'.

I've read that this is because both <i> and <b> are valid html5 tags. Does anyone know of a way of forcing TinyMCE to use '<em>' instead of '<i>' when pasting from Word?