Monk using spear at 17th level, is the spear now Versatile or does Martial arts override it?

@JeremyECrawford Monk using spear @ 17th level for 1d10 damage per hit. Is the spear now Versatile (1d12), or does Martial arts override it?

— Nathaemius Varrowe (@dmvarrowe69) April 16, 2016

You decide whether to use the Martial Arts die or the monk weapon's die. No effect on the weapon's properties. #DnD https://t.co/wmiySYjY6M

— Jeremy Crawford (@JeremyECrawford) April 22, 2016