Brushes cannot be enchanted

When trying to enchant a brush with /enchant @p unbreaking 3 or /enchant @p mending while holding the brush, an error message pops up saying "The selected enchantment can't be added to the target item: <player's gamertag>". A Brush also cannot be enchanted via an anvil when being "combined" with an unbreaking 3 / mending book.