Revitalize tooltip is bugged

Just played a game with Zac and the Revitalize rune for the extra blob healing and around 20 mins I noticed I had "-1453" bonus healing. Turns out Revitalize counts health costs as negative healing and subtracts 5% of the cost from the tooltip amount. The actual health cost isn't affected so I think it's only the tooltip that's bugged.

Also Revitalize counts the healing from your fountain, even if you're already at full health. I was standing in fountain with full health and the tooltip for Revitalize was going up ~5 per second. I guess it's not a bug but it makes the tooltip misleading.