Console game pricing has some inconsistency, and now one of the big publishers is explaining why.

Publisher Ubisoft reported the results of its fiscal Q1 today. And during a conference call with investors to discuss the financials and it’s more than $60 million in digital sales, an analyst asked a question that a lot of gamers probably have: Why do digital games cost so much more than the physical version on consoles?

For example, if you were to go buy the disc copy of Ubisoft’s Assassin’s Creed: Unity for PlayStation 4, here is what you’d pay at various online and brick-and-mortar retailers:

And here’s what you’d pay for a digital copy:

That’s twice as much for a download. And Ubisoft chief executive officer Yves Guillemot explained why that is.

“Digital games don’t react as fast on console as they do on PC,” said Guillemot. “What we can say is that when games are older than one year, digital is a lot more dynamic on console because there are less units in stores. It’s a new business and new trend.”

And keeping the pressure on physical sales is really important for Ubisoft.

“We want to get rid of the stocks in stores before lowering the price on digital,” said Guillemot.

So that $20 penalty you’re paying for downloading a game is really all about inventory management for the publisher. It needs to keep retailers happy so they don’t regret placing big orders for Ubisoft games. That ensures they’ll come back to make big orders in the future as well.

But Guillemot thinks this scenario is only temporary. It will only last for as long as physical is the dominant way to purchase games for Xbox One and PlayStation 4. Right now, when a game is available at launch as both a disc and a digital download, the physical version makes up between 80 percent to 85 percent of all sales.

“We think [pricing] will get more inline with time,” said Guillemot. “If you look at the PC trend, I think you will see that on consoles. But you’ll have to wait for that to happen at the same speed.”