Veigar's passive isn't enough

Veigar, even now, is one of my favorite mid laners, but the mana problems are starting to become more glaring with every game I play with him.

The emphasis on farming up as much AP as possible as fast as possible means that Veiger will practically be using Q every time it's off cooldown, adding to the mix, when he goes up against a lane bully, he has to make liberal usage of his cage to keep the opposing laner off him. What this ends up meaning is that until I get my mana item I spend the majority of the laning phase sitting at critically low mana. My last game my jungler failed to gank twice because I just didn't have the mana to help him. He couldn't really share his blue buff because he was Amumu. Q scales so hard with levels compared to the rest of his kit that you HAVE to max it, meaning Veigar ends up blowing 80 mana every 5 seconds by level 9.

Maybe you guys could make the passive scale with level or something?