Aatrox passive tooltip shows wrong amount of AD when Sterak's is bought

Sterak's gage increases the AD increase displayed on Aatrox's passive tooltip, but it doesn't actually increase the amount of AD he gets.

At level 1 with no runes or masteries: AD without Sterak's: 60 Passive tooltip without Sterak's: 15 AD after passive proc without Sterak's: 75

60 + 15 = 75

With Sterak's bought: AD with Sterak's: 75 Passive tooltip with Steraks: 19 AD after passive proc with Sterak's: 91

75 + 19 = 94, not 91

It's really weird that the same equation for calculating the increased base AD isn't used for both the passive and it's tooltip. RIP aatrox